- Create core/__init__.py
- Create core/models.py with all domain dataclasses:
  - Bounty (base class)
  - GroupBounty (extends Bounty)
  - PersonalBounty (extends Bounty)
  - TrackedBounty
  - GroupData
  - TrackingData
  - UserData
- Create tests/test_models.py with 15 passing tests

Fixes #5

@@ -0,0 +19,4 @@
+class GroupBounty(Bounty):
+    """Bounty created in a group context."""
+
+    created_by_user_id: int

@@ -0,0 +43,4 @@
+
+    group_id: int
+    bounties: list[GroupBounty]
+    next_id: int

@@ -0,0 +47,4 @@
+
+
+@dataclass
+class TrackingData:

@@ -0,0 +55,4 @@
+
+
+@dataclass
+class UserData:

@@ -0,0 +42,4 @@
+        assert b.link is None
+        assert b.due_date_ts is None
+
+    def test_bounty_comparison(self):

@@ -0,0 +17,4 @@
+    link: Optional[str]
+    due_date_ts: Optional[int]
+    created_at: int
+    created_by_user_id: Optional[int] = None

@@ -0,0 +21,4 @@
+
+
+@dataclass
+class TrackedBounty:

@@ -0,0 +37,4 @@
+    next_id is used to generate unique bounty IDs within this room.
+    """
+
+    room_id: int

@@ -0,0 +44,4 @@
+
+
+@dataclass
+class TrackingData:

@@ -0,0 +32,4 @@
+
+    bounty_id: int
+    created_at: int
+    room_id: int

@@ -0,0 +60,4 @@
+    TrackingData is the container, TrackedBounty is the item.
+    """
+
+    group_id: int