fix: Leonardo v2026.2.26 startup — add filemain secrets provider to openclaw.json

Root cause: Molty's secrets migration wrote tokenRef to Leonardo's auth-profiles.json
on the shared volume, but didn't add the filemain provider to Leonardo's openclaw.json.
v2026.2.26 enforces fail-fast on missing secret providers (v2026.2.25 was lenient).
Fix: inject provider config via Railway start command (Lesson vignesh07#69). All agents now on v2026.2.26.

Author: Molty

state/openclaw-fleet-version.json

@@ -12,11 +12,6 @@
   "leonardo": {
     "current": "v2026.2.26",
     "last_good": "v2026.2.25",
-    "updated_at": "2026-02-27T08:56:16.382207+08:00",
-    "pending_update": null,
-    "pending_since": null,
-    "rollback_reason": "v2026.2.26 gateway startup failure (500 timeout)",
-    "rollback_to": "v2026.2.25",
-    "rollback_at": "2026-02-27T12:18:41.774963+08:00"
+    "updated_at": "2026-02-27T12:22:03.880893+08:00"
   }
 }