Add Gitea Actions runner for automated CI/CD pipeline

- Runner deployment with host mode execution and kubectl access
- RBAC for creating Kaniko build pods
- Workflow triggers on push to main: Kaniko build → registry push → gitops update → ArgoCD sync

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infrastructure/gitea-runner/runner-config.yaml

@@ -0,0 +1,20 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: runner-config
+  namespace: build
+data:
+  config.yaml: |
+    log:
+      level: info
+    runner:
+      file: .runner
+      capacity: 1
+      timeout: 1h
+      labels:
+        - "ubuntu-latest:host"
+        - "self-hosted:host"
+    cache:
+      enabled: false
+    host:
+      workdir_parent: /tmp/actions