Deployment token rejected with "BadRequest: No matching Static Web App was found" — reproducible via Portal, CLI, and official SWA CLI (resource otherwise healthy)

## Describe the bug

Deployments to our Static Web App (`mrb-dashboard`) have been consistently failing with:

```
The content server has rejected the request with: BadRequest
Reason: No matching Static Web App was found or the api key was invalid.
```

This happens **regardless of deployment method** — we've ruled out every client-side cause we could think of (see "What we've tried" below). The resource itself is healthy and reachable via ARM/CLI/Portal (it's live and serving traffic at its custom domain), so this looks like a backend/content-server-side issue specific to this resource, not a token or configuration problem on our end.

## Resource details

- Resource ID: `/subscriptions/fbfb874b-7c4c-4b16-8db4-8692b58ebf99/resourceGroups/mrb-dashboard-rg/providers/Microsoft.Web/staticSites/mrb-dashboard`
- Name: `mrb-dashboard`
- Default hostname: `agreeable-desert-0ed1f2510.7.azurestaticapps.net`
- Custom domain: `dashboards.mrbstorage.com` (live and serving the last successful deployment)
- Location: Central US
- SKU: Free
- A `DeploymentId` from one of the failed GitHub Actions runs: `50f33347-d8f1-4074-bb27-b49d5ea87fed`

## What we've tried (all failed with the exact same BadRequest)

1. Reset the deployment token via the Azure Portal ("Manage deployment token" → Reset), updated the corresponding GitHub Actions repository secret (`AZURE_STATIC_WEB_APPS_API_TOKEN_AGREEABLE_DESERT_0ED1F2510`), re-ran the workflow.
2. Deleted and recreated the GitHub Actions secret from scratch (in case of a copy/paste issue), same result.
3. Removed a stray OIDC (`github_id_token`) flow from the workflow that was triggering an unrelated `Unexpected input(s)` warning — this fixed the warning but not the underlying deploy failure.
4. Disconnected the GitHub source-control link at the resource level via Azure CLI:
```
az staticwebapp disconnect -n mrb-dashboard -g mrb-dashboard-rg
```
Confirmed via `az staticwebapp show` that `repositoryUrl`, `repositoryToken`, and `provider` are now `null`/`"None"`.
5. Reset the API key directly via CLI (bypassing the portal UI entirely):
```
az staticwebapp secrets reset-api-key -n mrb-dashboard -g mrb-dashboard-rg
az staticwebapp secrets list -n mrb-dashboard -g mrb-dashboard-rg --query "properties.apiKey" -o tsv
```
6. Used that freshly-generated token to deploy directly with the official SWA CLI (`@azure/static-web-apps-cli` v2.0.10), completely bypassing GitHub Actions:
```
swa deploy /tmp/swatest --deployment-token "$TOKEN" --env production
```
This also failed with the identical error:
```
✖ The content server has rejected the request with: BadRequest
✖ Reason: No matching Static Web App was found or the api key was invalid.
✖ Deployment failed with exit code 1
```

Since step 6 uses a token generated moments earlier via `az staticwebapp secrets reset-api-key`, and is deployed with Microsoft's own official CLI with no GitHub involvement at all, we believe this rules out any client-side token/secret/workflow issue and points to a desync between the ARM control plane and the deployment content server for this specific resource.

## Expected behavior

A deployment token generated via `az staticwebapp secrets reset-api-key` (or the Portal's "Reset token") should be accepted by the content server for the resource it was generated for.

## Steps to reproduce

Unknown on our end — this resource was deploying successfully via GitHub Actions until our most recent attempt (the workflow run with `DeploymentId: 50f33347-d8f1-4074-bb27-b49d5ea87fed`, first seen failing on 2026-07-29). No changes were made to the resource's region, SKU, or hosting plan around that time as far as we're aware. The site itself (`dashboards.mrbstorage.com`) is still live and serving the last successful deployment.

## Additional context

- This is a Free-tier resource, so we don't have a support plan to open a formal Azure support ticket — filing here per the guidance in the CLI error output and prior similar issues in this repo.
- We also tried the Portal's built-in **"Diagnose and solve problems"** tool on this resource. It hangs for a while and then fails with a generic `Sorry, an error occurred. Please refresh the page and try again.` — it's unable to complete a diagnostic pass on this resource at all, which seems consistent with something being broken in the backend service for this specific Static Web App rather than a client-side config issue.
- Happy to provide additional diagnostic output (further CLI output, HAR files, etc.) on request.

Start by reproducing the failure with `az staticwebapp secrets reset-api-key` followed by the official `swa deploy` command, then compare the resource state from `az staticwebapp show` with the deployment response. The issue is done when the regenerated token is accepted for `mrb-dashboard`, or when the backend cause and required remediation are identified.

Written by the indexing model from the issue text.