Add integration testing guide and prompts

- docs/workflow/INTEGRATION-TESTING.md - Full guide on integration testing
  - What it is vs unit/e2e tests
  - 5 principles to test per integration point
  - Folder structure suggestions
  - Self-improving loop for human findings
- integration-tests/ - Template for project's integration tests
  - README.md - What to test (Feynman fills per project)
  - package.json - Test runner setup
  - scripts/setup.sh - Service startup
  - scripts/teardown.sh - Cleanup
- docs/workflow/WORKFLOW.md - Added integration testing references
- docs/workflow/AGENT-PROMPTS.md - Added integration testing prompts
- docs/workflow/INDEX.md - Updated file structure

integration-tests/README.md

@@ -0,0 +1,102 @@
+# Integration Tests
+
+**This file documents what integration tests should exist in this project.**
+
+Feynman will fill this out by surveying the codebase. Human reviews and approves.
+
+---
+
+## Integration Points
+
+| # | From System | To System | What We Test | Status |
+|---|------------|----------|--------------|--------|
+| — | — | — | — | — |
+
+---
+
+## What to Test Per Integration Point
+
+For each integration point above, document what to test:
+
+### Integration Point #1: [FILL: System A ↔ System B]
+
+**What to test:**
+
+1. **Happy Path**
+   - [ ] TODO
+
+2. **Data Integrity**
+   - [ ] TODO
+
+3. **Error Handling**
+   - [ ] TODO
+
+4. **Auth**
+   - [ ] TODO
+
+5. **Timing/Async**
+   - [ ] TODO
+
+---
+
+## Known Integration Test Gaps
+
+<!-- Issues or TODOs for missing tests -->
+
+- TODO: [Describe missing test]
+
+---
+
+## Tests to Implement
+
+| # | Test Description | Integration Point | Status |
+|---|-----------------|------------------|--------|
+| 1 | TODO | TODO | TODO |
+
+---
+
+## Human Findings (Regression Tests Added)
+
+When human finds a bug during manual testing, document it here. Agent implements a regression test.
+
+| Date | What Human Found | Test Added? | Test File |
+|------|------------------|-------------|-----------|
+| — | — | — | — |
+
+---
+
+## How to Run Tests
+
+```bash
+# Install dependencies
+pnpm install
+
+# Setup services (if needed)
+pnpm run test:integration:setup
+
+# Run all integration tests
+pnpm run test:integration
+
+# Run specific integration point tests
+pnpm run test:integration -- --grep "auth"
+
+# Teardown (if needed)
+pnpm run test:integration:teardown
+```
+
+---
+
+## Services Required for Tests
+
+<!-- Document what services need to be running for tests to pass -->
+
+| Service | How to Start | Port | Notes |
+|---------|-------------|------|-------|
+| — | — | — | — |
+
+---
+
+## Notes
+
+<!-- Any project-specific notes about testing -->
+