fix: resolve Alembic multiple heads

The terminal_sessions migration and drop_tool_configs migration both pointed
to add_tool_definition_manifests as their down_revision, creating two heads.
Update drop migration to depend on terminal_sessions instead, restoring a
single linear chain.

apps/api/src/services/manifest_compiler.py

@@ -350,9 +350,7 @@ def compute_image_tag(tool_name: str, manifest: dict) -> str:
     return f"headquarter/{safe_name}-{hash_suffix}:latest"
 
 
-def merge_with_config(
-    manifest: dict, profile: dict | None = None
-) -> dict:
+def merge_with_config(manifest: dict, profile: dict | None = None) -> dict:
     """Merge ConfigProfile overrides into a manifest.
 
     Args: