fix(macos_container): mount supervise db's parent dir, not the file

Apple's `container run --mount type=bind` only accepts directory
sources — a file source fails with "path '<file>' is not a
directory". Move the sqlite db into its own ~/.bot-bottle/db/
subdirectory so it can be bind-mounted the same way the CA/routes
mounts already are, without exposing the rest of ~/.bot-bottle.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

bot_bottle/backend/macos_container/launch.py

@@ -405,7 +405,15 @@ def _sidecar_mounts(
 
     sp = plan.supervise_plan
     if sp is not None:
-        mounts.append((str(sp.db_path), DB_PATH_IN_CONTAINER, False))
+        # `container run --mount type=bind` only accepts directory
+        # sources (a file source fails with "is not a directory") —
+        # mount db_path's dedicated parent dir instead of the file
+        # itself, same as the CA/routes mounts above.
+        mounts.append((
+            str(sp.db_path.parent),
+            str(Path(DB_PATH_IN_CONTAINER).parent),
+            False,
+        ))
 
     return tuple(mounts)