ci(mcp): image tag unique per run so docs-only redeploys roll a new revision

A redeploy at an unchanged code sha (the documented way to refresh the
baked-in search_docs corpus) built an image with the identical tag;
az containerapp update saw the same image reference and created no
revision, so the verify step timed out against the old build (run
33215583943). Tag = sha-run_number; build commit/version stay separate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/deploy-mcp.yml

@@ -11,7 +11,11 @@ env:
   ACR_NAME: autopilotmonitoreuacr
   CONTAINER_APP_NAME: autopilotmonitor-mcp
   RESOURCE_GROUP: ${{ secrets.AZURE_MCP_RESOURCE_GROUP }}
-  IMAGE_TAG: ${{ github.sha }}
+  # Unique per RUN, not per commit: the docs corpus is baked into the image, so a
+  # docs-only redeploy at an unchanged code sha must still produce a new image
+  # reference — with a sha-only tag `az containerapp update` saw the same image
+  # and silently created no revision (2026-08-28).
+  IMAGE_TAG: ${{ github.sha }}-${{ github.run_number }}
   HEALTH_URL: https://mcp.autopilotmonitor.com/health
   VERSIONS_CONTAINER: https://autopilotmonitoreu.blob.core.windows.net/versions
   PACKAGE_JSON: src/McpServer/autopilot-monitor-mcp/package.json
@@ -28,8 +32,9 @@ jobs:
       # baked into the image as the search_docs corpus (see the Dockerfile). No
       # token is needed. Checking it out here rather than vendoring it keeps the
       # docs single-sourced — but it also means EDITING THE DOCS DOES NOT UPDATE A
-      # RUNNING SERVER; this workflow must be re-run. /health reports the SHA
-      # captured below so that staleness is checkable.
+      # RUNNING SERVER; this workflow must be re-run (IMAGE_TAG is per run so the
+      # re-run actually rolls a new revision). /health reports the SHA captured
+      # below so that staleness is checkable.
       - name: Check out documentation bundle
         uses: actions/checkout@v7
         with: