Add searchable admin audit history

server/db.js

@@ -265,6 +265,17 @@ export async function initDb() {
       created_at   INTEGER NOT NULL DEFAULT (unixepoch()),
       last_used_at INTEGER
     );
+
+    CREATE TABLE IF NOT EXISTS audit_log (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      ts INTEGER NOT NULL DEFAULT (unixepoch()),
+      actor TEXT NOT NULL,
+      action TEXT NOT NULL,
+      target TEXT NOT NULL DEFAULT '',
+      detail TEXT NOT NULL DEFAULT '{}'
+    );
+    CREATE INDEX IF NOT EXISTS idx_audit_ts ON audit_log (ts DESC, id DESC);
+    CREATE INDEX IF NOT EXISTS idx_audit_actor_action ON audit_log (actor, action, ts DESC);
   `);
   await migrateVideoMeta();
   // Uploads shared from devices (PWA share target): who sent it, and whether it