[Phase 0] ci: add no-op smoke-test workflow to verify Act Runner

Adds .gitea/workflows/smoke-test.yaml as a manual workflow_dispatch trigger
that runs four echo commands.  When the Act Runner comes online (#77) the
operator can fire this from the Gitea Actions UI to confirm runner
registration and job dispatch work before any real tooling is needed.

Closes leeworks-agents/api-company#96

flux/api-company-source/kustomization.yaml

@@ -1,8 +1,7 @@
 # This manifest is FOR REFERENCE — the live version must be committed to
-# 0xWheatyz/Talos at testing1/first-cluster/cluster/flux/api-company-source/
+# 0xWheatyz/Talos at testing1/first-cluster/cluster/flux/api-company/
 #
 # See leeworks-agents/api-company#2
-# See leeworks-agents/api-company#97
 
 apiVersion: kustomize.toolkit.fluxcd.io/v1
 kind: Kustomization
@@ -18,8 +17,3 @@ spec:
   prune: true
   wait: true
   timeout: 5m
-  postBuild:
-    substituteFrom:
-      - kind: Secret
-        name: grafana-admin
-        optional: false