fix(state): VACUUM is gated by the same quarantine rule as the checkpoints

Follow-up to #106315. vacuum() ran PRAGMA wal_checkpoint + VACUUM + wal_checkpoint(TRUNCATE) on
self._conn with no quarantine check; the only guard it inherited (optimize_fts raising
DeletedWalGenerationError) was swallowed by its own try/except and the rewrite proceeded on the
split-brain handle. Mutation on main: vacuum() returned 2 and rewrote pages after the write stop.

hermes_state_maintenance.py

@@ -336,7 +336,14 @@ class SessionMaintenanceMixin:
         """VACUUM to reclaim space after large deletes (SQLite never shrinks on its own).
         Takes an exclusive lock — callers must ensure no other writers are active.  FTS5
         segments are merged first (:meth:`optimize_fts`) so their pages are reclaimed too;
-        returns the number of FTS indexes optimized (0 on merge failure / no FTS)."""
+        returns the number of FTS indexes optimized (0 on merge failure / no FTS). A quarantined
+        handle (corrupt image, replaced file, lost WAL generation) never checkpoints or rewrites
+        pages: the halt raised by ``optimize_fts`` would otherwise be swallowed below and the
+        VACUUM would proceed on the split-brain handle (#105670)."""
+        quarantine_reason = self._quarantine_reason()
+        if quarantine_reason is not None:
+            logger.warning("Skipping VACUUM for %s: this handle observed %s.", self.db_path, quarantine_reason)
+            return 0
         optimized = 0
         try:
             optimized = self.optimize_fts()  # manages its own lock