feat: Case format and skill drafts

- Case format: YAML schema for investigation cases
  - title, briefing, evidence, suspects
  - Truth separated to truth.enc (base64 encoded)
  - Images: path or URL

- Two skills:
  - detective-play: Play investigation cases
  - detective-create: Create new cases

- Folder structure:
  - ~/.hermes/detective/cases/ for all cases
  - Each case: case.yaml + truth.enc + images/

- Truth protection: base64 encoded, decode only after playing

docs/case-format-draft.md

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+# Case Format (YAML Schema) — Draft v1
+
+**Date:** 2026-04-19  
+**Status:** Draft  
+**Purpose:** Define structure for investigation cases
+
+---
+
+## Case File Structure
+
+```yaml
+case:
+  id: "easy-01"
+  title: "The Missing Heirloom"
+  difficulty: easy
+  difficulty_description: "A straightforward case with obvious clues"
+  
+  # Case metadata
+  version: "1.0"
+  author: "Hermes Team"
+  created_at: "2026-04-19"
+  
+  # What the Chief sees at the start
+  briefing:
+    narrative: |
+      The Hartwell family heirloom—a ruby brooch passed down 
+      for generations—has vanished from the family vault. 
+      The vault was locked, and only three people had access.
+    suspects_count: 2
+    
+  # Evidence available from the start
+  evidence:
+    - id: "evidence-01"
+      name: "Crime Scene Photo"
+      type: photo
+      file: "images/evidence-01.jpg"
+      description: "The open vault in the family study"
+      triggers_witness: false  # Available immediately
+      hint_level: too_obvious  # How hidden the clue is
+      
+    - id: "evidence-02"
+      name: "Security Log"
+      type: document
+      file: "images/evidence-02.jpg"
+      description: "Digital log of vault access"
+      triggers_witness: false
+      hint_level: barely_obvious
+      
+    - id: "evidence-03"
+      name: "Witness Testimony"
+      type: document
+      file: "images/evidence-03.jpg"
+      description: "Maid's statement to police"
+      triggers_witness: true  # Only available after this is examined
+      hint_level: not_too_obvious
+  
+  # Suspects
+  suspects:
+    - id: "suspect-01"
+      name: "Eleanor Hartwell"
+      photo: "images/suspect-01.jpg"
+      description: |
+        The eldest daughter. Had keys to the vault.
+        Recently denied inheritance due to family dispute.
+      examined: false  # Initially not examined
+      
+    - id: "suspect-02"
+      name: "James Butler"
+      photo: "images/suspect-02.jpg"
+      description: |
+        The family butler. Has served for 20 years.
+        Seen near the vault that morning.
+      examined: false
+
+  # How evidence links to truth
+  truth:
+    # What the creator intended
+    summary: |
+      Eleanor Hartwell took the brooch because she was denied 
+      inheritance. She hid it in the garden shed to claim insurance.
+    
+    # Criteria for alignment scoring
+    criteria:
+      - id: "criterion-01"
+        description: "Identified Eleanor as main suspect"
+        weight: 40
+        
+      - id: "criterion-02"
+        description: "Understood motive (inheritance dispute)"
+        weight: 30
+        
+      - id: "criterion-03"
+        description: "Found the hiding spot (garden shed)"
+        weight: 30
+    
+    # Evidence that supports each criterion
+    evidence_map:
+      criterion-01:
+        supporting: ["evidence-01", "suspect-01"]
+      criterion-02:
+        supporting: ["evidence-02", "evidence-03"]
+      criterion-03:
+        supporting: ["evidence-03"]  # Hidden in testimony
+
+  # Witness appearance rules
+  witness:
+    mode: "default"  # "default" | "triggered" | "manual"
+    
+    # For "triggered" mode - which evidence triggers witness
+    triggers:
+      - evidence_id: "evidence-03"
+        testimony: |
+          "I remember now—Miss Eleanor was arguing with her father 
+          about the inheritance just last week. She seemed furious.
+          And this morning, I saw her walking toward the garden..."
+
+  # Case settings
+  settings:
+    witness_always_talks: true  # If true, Witness describes everything. If false, only what Chief asks.
+    allow_skip: true           # Can skip evidence
+    max_turns: 10             # Soft limit
+```
+
+---
+
+## Field Explanations
+
+### Required Fields
+
+| Field | Description |
+|-------|-------------|
+| `case.id` | Unique identifier (slug) |
+| `case.title` | Display name |
+| `case.difficulty` | easy, medium, hard, hardcore, impossible |
+| `case.briefing` | Initial narrative + suspect count |
+| `case.evidence` | List of evidence items |
+| `case.suspects` | List of suspects |
+| `case.truth` | Creator's intended story + criteria |
+
+### Evidence Types
+
+| Type | Kimi Sees |
+|------|-----------|
+| `photo` | Visual analysis |
+| `document` | Text extraction + analysis |
+| `video` | Frame-by-frame (if supported) |
+| `audio` | Transcription + analysis |
+
+### Hint Levels
+
+| Level | Meaning |
+|-------|---------|
+| `too_obvious` | Player will find it easily |
+| `barely_obvious` | Requires some exploration |
+| `not_too_obvious` | Hidden, requires attention |
+
+### Witness Modes
+
+| Mode | Behavior |
+|------|---------|
+| `default` | Witness appears with all triggered evidence |
+| `triggered` | Witness only appears when evidence triggers |
+| `manual` | Chief must explicitly request witness |
+
+---
+
+## Example Evidence Item
+
+```yaml
+- id: "evidence-01"
+  name: "Crime Scene Photo"
+  type: photo
+  file: "images/evidence-01.jpg"
+  description: "The open vault in the family study"
+  triggers_witness: false
+  hint_level: too_obvious
+```
+
+---
+
+## Questions / Decisions Needed
+
+1. **Witness modes** — Do we need all three? Or simplify?
+2. **Criteria weights** — Should they always sum to 100%?
+3. **Evidence linking** — Is `evidence_map` the right approach for alignment?
+4. **Optional fields** — What should be required vs optional?
+5. **Images** — How to reference? Path? URL?
+
+---
+
+## Starter Case Example
+
+For the first proof-of-concept, we could create:
+
+```
+easy-01: "The Missing Heirloom"
+- 3 evidence items
+- 2 suspects
+- 3 criteria
+- Simple truth: Someone stole something for a reason
+```
+
+---
+
+**Does this format make sense? What should we add/remove?**

docs/skills/detective-create/SKILL.md

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+---
+name: detective-create
+description: Create mystery investigation cases for Hermes Detective Agency
+---
+
+# Detective Case Creator
+
+Help users create mystery investigation cases.
+
+## Case Structure
+
+Create a folder in `~/.hermes/detective/cases/<case-name>/`
+
+Each case needs:
+```
+<case-name>/
+├── case.yaml      # Case data
+├── truth.enc      # Encoded truth
+└── images/        # Evidence images
+```
+
+## Case YAML Format
+
+```yaml
+title: "Case Title Here"
+
+briefing:
+  narrative: |
+    The opening story. Set the scene for the investigation.
+
+evidence:
+  - id: "evidence-01"
+    name: "Evidence Name"
+    image: "images/evidence-01.jpg"
+    description: "Brief description"
+
+  - id: "evidence-02"
+    name: "Another Evidence"
+    image: "images/evidence-02.jpg"
+    description: "Brief description"
+
+suspects:
+  - id: "suspect-01"
+    name: "Suspect Name"
+    photo: "images/suspect-01.jpg"
+    description: "Background info"
+```
+
+## How to Encode Truth
+
+The truth must be encoded to `truth.enc`:
+
+```python
+import base64
+
+truth = """---
+summary: |
+  What actually happened in the case.
+key_points:
+  - "Key point 1"
+  - "Key point 2"
+---"""
+
+encoded = base64.b64encode(truth.encode()).decode()
+# Write encoded to truth.enc
+```
+
+## Creating Images
+
+Images can be:
+- Real photos or documents
+- AI-generated (use Pollinations or similar)
+- Clear and readable
+- JPG or PNG format
+- Not too large (under 1MB each)
+- Named clearly (evidence-01.jpg, suspect-01.jpg)
+
+## Guidelines
+
+- Case should be solvable with the evidence provided
+- Truth should align with evidence (no hidden info)
+- Include 2-4 evidence items and 2-3 suspects for Easy

docs/skills/detective-play/SKILL.md

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+---
+name: detective-play
+description: Play mystery investigation cases powered by Kimi Vision
+---
+
+# Detective Play
+
+You are a detective agency assistant. Help the user play mystery investigation cases.
+
+## Cases Location
+
+All cases are stored in:
+```
+~/.hermes/detective/cases/
+```
+
+Each case is a folder containing:
+- `case.yaml` — Evidence, suspects, briefing (NO truth)
+- `truth.enc` — Encoded solution
+- `images/` — Evidence images
+
+## How to Play
+
+1. Look at available cases in `~/.hermes/detective/cases/`
+2. Tell the user what cases are available
+3. User picks a case
+4. Load the case.yaml from that folder
+5. Present the briefing narrative
+6. Let the user examine evidence (show images from images/ folder)
+7. Use Kimi Vision to analyze images when asked
+8. Help theorize based on evidence
+9. When user is ready, help them build and submit their theory
+
+## When User Asks About Truth
+
+Only reveal truth AFTER user has formed and submitted their theory.
+
+To decode truth:
+```python
+import base64
+with open('truth.enc', 'r') as f:
+    encoded = f.read().strip()
+decoded = base64.b64decode(encoded.encode()).decode()
+print(decoded)
+```
+
+## Important
+
+- NEVER read truth.enc before the user is done investigating
+- Case format: case.yaml (evidence + suspects only)
+- Images are in the images/ subfolder
+- Kimi Vision can analyze images when you call it