simplify(compat): hermes_state — drop 81 re-exports + 3 registry aliases + 3 shims, repoint 45 callers + 60 test files

hermes_state.py: delete every '# noqa: F401 (re-exported...)' import block (hermes_state_common/errors/guard/
readpool/sessions/fts/dbfile/wal/repair/registry + agent.context_compressor _DB_PERSISTED_MARKER_KEY); keep
only the names hermes_state.py itself uses, without noqa.
hermes_state_registry.py: drop get_shared_session_db/release_shared_session_db/close_shared_session_dbs
aliases; every caller (gateway/, tools/, tui_gateway/, cron/, mcp_serve, run_agent, tests) now imports
acquire/release/close_all/release_or_close from hermes_state_registry.
hermes_state_titles.py: drop set_auto_title_if_empty shim (title_generator keeps its getattr fallback).
Re-remove shim-only names restored by 34abf954bd: latest_user_message_row_id (tests call
latest_message_row_id(key, role='user'); role-targeting assertions kept) and get_session_activity (tests
build the snapshot via agent.session_activity.build_activity_snapshot over db.get_session(sid)).
hermes_state_wal._log_once resolves its dedupe sets as module globals instead of via hermes_state;
hermes_state_repair helpers call module globals directly (tests patch hermes_state_repair.<name>).
Frozen updater surface untouched (update_cmd_maint imports only SessionDB from hermes_state).

hermes_state_sessions.py

@@ -601,21 +601,6 @@ class SessionSessionsMixin:
             ("", ActivityProvenance.UNKNOWN.value, session_id), patience_s=self._ACTIVITY_WRITE_PATIENCE_S,
         )
 
-    def get_session_activity(self, session_id: str) -> Optional[Dict[str, Any]]:
-        """Return the durable activity snapshot for *session_id*, or None."""
-        if not session_id:
-            return None
-        row = self.get_session(session_id)
-        if not row:
-            return None
-        from agent.session_activity import build_activity_snapshot
-
-        return build_activity_snapshot(
-            last_activity_at=row.get("last_activity_at"),
-            last_activity_description=row.get("last_activity_description"),
-            last_activity_provenance=row.get("last_activity_provenance"),
-        )
-
     def update_session_meta(
         self, session_id: str, model_config_json: str, model: Optional[str] = None,
     ) -> None: