Stage: run the per-member key seed from the image, not the volume

Ready to build, not yet deployed — deploying the repointed scheduler command
without the new image would break the seed on schedule, which is why this sits on
a branch with the ordering written down.

- Dockerfile: COPY sync-keys.js /app/code/sync-keys.js; rule 3 in the header now
  states the one exception (operational scripts that must not depend on a volume).
- CloudronManifest.json: scheduler command repointed to /app/code/sync-keys.js.
- README: ordering (build -> deploy -> verify -> delete the volume copy), and the
  table row moved from the volume layer to the image layer.

After deploy: delete /app/data/sync-keys.js, but keep it until you are past the
rollback window — the previous image tag still runs the volume copy.

README.md

@@ -34,7 +34,7 @@ md5sum librechat.yaml mcp/server.py mcp/image_server.py
 | Env vars (env-file wins!) | `/app/data/env` (volume, sourced LAST by start.sh) | yes | documented below |
 | Env vars (Cloudron-managed) | `cloudron env` (process env) | yes | documented below |
 | MCP servers | `/app/data/mcp/server.py` + `mcp/image_server.py` (volume) | yes | `mcp/` |
-| Per-member key seed | `/app/data/sync-keys.js` (volume; run by the manifest's `scheduler` task) | yes | `sync-keys.js` |
+| Per-member key seed | `sync-keys.js` baked into the image at `/app/code/sync-keys.js` (run by the manifest's `scheduler` task) | no — rebuilt per image | `sync-keys.js` |
 | Brand assets + branding CSS/JS | baked into image overlay | no — rebuilt per image | `assets/` |
 | `CloudronManifest.json` | repo only (controls what `cloudron update` deploys) | n/a | official appstore manifest **except `dockerImage`** |
 
@@ -333,11 +333,21 @@ member's own portal-provisioned key automatically:
 "scheduler": {
   "librechat_key_sync": {
     "schedule": "*/10 * * * *",
-    "command": "cd /app/code/librechat/api && node /app/data/sync-keys.js"
+    "command": "cd /app/code/librechat/api && node /app/code/sync-keys.js"
   }
 }
 ```
 
+The script is **baked into the image** (`COPY sync-keys.js /app/code/…`), so it
+cannot be lost with a volume restore and cannot drift from this repo.
+
+**Ordering matters on the first deploy of this change:** build the image → deploy
+(pin the new tag in the manifest first — the manifest's repointed command ships
+in the same `cloudron update`) → verify (`./release.sh verify` checks that the
+command path exists in the running image) → only then delete the volume copy
+`/app/data/sync-keys.js`, because rolling back to the previous image tag needs it
+back. After that, a change to this script requires a rebuild, not a volume push.
+
 Seeding therefore depends on nothing outside this app — it previously ran from a
 steward cron on another machine, which made a member-facing function depend on
 that machine's uptime and paths.