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

tests/test_ports.py

@@ -48,6 +48,20 @@ class SimpleRoomStorage:
                     return b
         return None
 
+    def list_bounties(self, room_id: int) -> list[Bounty]:
+        if room_id not in self._rooms:
+            return []
+        return [b for b in self._rooms[room_id].bounties if b.deleted_at is None]
+
+    def list_all_bounties(
+        self, room_id: int, include_deleted: bool = True
+    ) -> list[Bounty]:
+        if room_id not in self._rooms:
+            return []
+        if include_deleted:
+            return self._rooms[room_id].bounties
+        return [b for b in self._rooms[room_id].bounties if b.deleted_at is None]
+
 
 class SimpleTrackingStorage:
     """Minimal mock without ensure_tracking - tests if track_bounty works without it.
@@ -119,6 +133,20 @@ class MockRoomStorage:
                     return b
         return None
 
+    def list_bounties(self, room_id: int) -> list[Bounty]:
+        if room_id not in self._rooms:
+            return []
+        return [b for b in self._rooms[room_id].bounties if b.deleted_at is None]
+
+    def list_all_bounties(
+        self, room_id: int, include_deleted: bool = True
+    ) -> list[Bounty]:
+        if room_id not in self._rooms:
+            return []
+        if include_deleted:
+            return self._rooms[room_id].bounties
+        return [b for b in self._rooms[room_id].bounties if b.deleted_at is None]
+
 
 class MockTrackingStorage:
     """Mock implementation of TrackingStorage for testing."""