Managed Functions deployment consistently fails: "Failed to deploy the Azure Functions" (build succeeds, deploy times out during polling)

### Describe the bug
Since 29 May 2026, every deployment of our Static Web App fails at the managed
Functions deployment step with:

The Oryx build and artifact upload succeed; the failure happens on the Azure side
during "Polling on deployment". The same `/api` code deployed successfully on
28 May 2026.

### Reproduction
1. Push to the linked branch (or open a PR) — workflow `Azure Static Web Apps CI/CD` runs.
2. Build + "Zipping/Uploading build artifacts" complete fine.
3. "Finished Upload. Polling on deployment." → Status: InProgress … → Status: Failed.
4. Job ends with "Failed to deploy the Azure Functions."

### Log excerpt

### Environment
- Static Web App: `tbp-dashboard`
- Region: West Europe *(verify on the resource Overview)*
- Plan: Standard *(adjust if Free)*
- API: managed functions, 5 functions, classic v3 model (function.json + index.js)
- Functions runtime: ~4, Node 20 (pinned via `platform.apiRuntime: "node:20"`)

### What we have already ruled out
- No `EnvironmentId` tag on the resource (Tags blade empty)
- Deployment token valid (upload + polling start succeed)
- No `FUNCTIONS_WORKER_RUNTIME` app setting
- `api_location` correct; `/api` contains valid v3 functions
- Environment variables present and correct
- No Service Health incident in our region
- Forcing a clean function redeploy via a `host.json` content change did **not** help
- Reproducible across 6+ re-runs on **both** preview and production environments

### Expected behavior
Managed Functions deploy succeeds as it did on 28 May 2026 with identical `/api` code.

### Additional context
The failure occurs at varying poll times (15s / 45s / 61s) rather than failing fast,
which suggests a backend timeout/flakiness in the managed Functions deployment rather
than a configuration error on our side. Requesting backend investigation.