feat: add list_bounties and list_all_bounties methods to storage adapter

Add filtering methods to JsonFileRoomStorage for Phase 2 soft delete support:
- list_bounties(room_id): returns only non-deleted bounties for normal queries
- list_all_bounties(room_id, include_deleted=True): returns all bounties for /recover

Update RoomStorage protocol to include the new methods.
Update mock classes in tests to pass isinstance checks.

Fixes #42

core/ports.py

@@ -40,6 +40,25 @@ class RoomStorage(Protocol):
         """Get a specific bounty from a room by ID."""
         ...
 
+    def list_bounties(self, room_id: int) -> list[Bounty]:
+        """List all non-deleted bounties in a room.
+
+        Soft-deleted bounties (where deleted_at is not None) are excluded.
+        """
+        ...
+
+    def list_all_bounties(
+        self, room_id: int, include_deleted: bool = True
+    ) -> list[Bounty]:
+        """List all bounties including or excluding soft-deleted.
+
+        Args:
+            room_id: The room ID
+            include_deleted: If True, return all bounties including soft-deleted.
+                           If False, return only non-deleted bounties.
+        """
+        ...
+
 
 @runtime_checkable
 class TrackingStorage(Protocol):