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

adapters/storage/json_file.py

@@ -140,6 +140,35 @@ class JsonFileRoomStorage:
 
         return None
 
+    def list_bounties(self, room_id: int) -> list[Bounty]:
+        """List all non-deleted bounties in a room.
+
+        This is the default method for normal queries - soft-deleted bounties
+        are excluded from results.
+        """
+        room_data = self.load(room_id)
+        if room_data is None:
+            return []
+        return [b for b in room_data.bounties if b.deleted_at is None]
+
+    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.
+                           Defaults to True for /recover functionality.
+        """
+        room_data = self.load(room_id)
+        if room_data is None:
+            return []
+        if include_deleted:
+            return room_data.bounties
+        return [b for b in room_data.bounties if b.deleted_at is None]
+
 
 class JsonFileTrackingStorage:
     """TrackingStorage implementation using JSON files.