feat: add author-username search to feed/gists/projects listings and partial-index migration

Extend `database.text_search_clause` with an `author_field` parameter that resolves username matches to user UIDs, enabling author-username search across the three public listings (`/feed`, `/gists`, `/projects`). Update the corresponding API docs and README route descriptions to reflect the new search scope. Add six partial indexes (`idx_comments_target_live`, `idx_votes_target_live`, `idx_reactions_target_live`, `idx_gists_live_created`, `idx_projects_live_created`, `idx_attachments_user_created_live`) to optimize filtered queries on non-deleted rows. Introduce a hot-settings cache (`_hot_settings`) with a 2-second TTL for `maintenance_mode`, `rate_limit_per_minute`, and `rate_limit_window_seconds`, plus a periodic rate-limit store sweep (`_sweep_rate_limit_store`) to evict stale IP entries every 60 seconds. Add `GZipMiddleware` to the FastAPI app for response compression.

devplacepy/services/base.py

@@ -401,11 +401,11 @@ class BaseService(ABC):
     def _metrics(self, state: dict) -> dict:
         raw = state.get("metrics")
         if not raw:
-            return {}
+            return self._safe_metrics()
         try:
             return json.loads(raw)
         except (ValueError, TypeError):
-            return {}
+            return self._safe_metrics()
 
     def describe(self) -> dict:
         state = self._read_state()