Add core/ports.py - Storage interfaces

Define abstract storage interfaces (Protocols):
- RoomStorage: for room/group bounties (load, save, add/update/delete/get_bounty)
- PersonalStorage: same operations for personal/DM bounties
- TrackingStorage: for tracking data (load, save, track/untrack_bounty)

core/__init__.py

@@ -6,10 +6,18 @@ from core.models import (
     RoomData,
     TrackingData,
 )
+from core.ports import (
+    RoomStorage,
+    PersonalStorage,
+    TrackingStorage,
+)
 
 __all__ = [
     "Bounty",
     "TrackedBounty",
     "RoomData",
     "TrackingData",
+    "RoomStorage",
+    "PersonalStorage",
+    "TrackingStorage",
 ]