Restore [self-hosted, host] runs-on; fix routing-loss regression

.gitea/workflows/deploy-stack.yml

@@ -77,13 +77,17 @@ on:
 
 jobs:
   deploy:
-    # Single-label `runs-on` (not the [self-hosted, <host>] array form). In
-    # Gitea/act_runner, the array is matched loosely — a runner advertising
-    # only `self-hosted` will pick up jobs intended for a specific host. Using
-    # the bare host label routes deterministically to the correct runner.
-    # Every runner advertises both `self-hosted` and its host short name (see
-    # Charlie/runners envs/<host>.env GITEA_RUNNER_LABELS).
-    runs-on: ${{ inputs.host }}
+    # Both labels required:
+    #   `self-hosted` — magic label that puts act_runner in host-execution
+    #     mode (no docker image pulled for the job container).
+    #   `<host>`       — the host short name. Each runner advertises its host
+    #     label uniquely so this disambiguates which runner picks up the job.
+    #
+    # Gitea's label matching IS supposed to be AND for arrays, but in
+    # practice the host label alone is more reliable. We keep both because
+    # dropping `self-hosted` makes act default to docker mode and pull an
+    # ubuntu image, which we don't want.
+    runs-on: [self-hosted, "${{ inputs.host }}"]
     steps:
       - name: Resolve stack path and ref
         id: resolve