feat: implement proto-gen platform

- Config loader with env var expansion and validation
- SQLite database with tasks and toolchain_versions tables
- Gitea REST API client for repository and branch operations
- K8s client for Job lifecycle management (with noop fallback for local dev)
- REST API: tasks CRUD, retry, plugins, version management
- Worker/scheduler with polling, concurrency control, and job tracking
- Static frontend: generate, tasks, settings pages
- Toolchain images: Go and Node.js Dockerfiles with entrypoint scripts
- Helm chart with deployment, service, configmap, ingress, PVC
- Multi-stage Dockerfile for service
- Unit tests for config, database, gitclient, k8s, api, worker
- E2E tests for idempotency, version switch, failure recovery

deploy/helm/proto-gen/templates/configmap.yaml

@@ -0,0 +1,24 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ .Release.Name }}-config
+data:
+  config.yaml: |
+    server:
+      addr: ":8080"
+    git:
+      type: gitea
+      base_url: "{{ .Values.git.baseUrl }}"
+      token: "${GIT_TOKEN}"
+    cluster:
+      kubeconfig: /etc/proto-gen/kubeconfig
+      namespace: {{ .Values.cluster.namespace }}
+      job_timeout: {{ .Values.cluster.jobTimeout }}
+      max_concurrent: {{ .Values.cluster.maxConcurrent }}
+    toolchain_registry: "{{ .Values.toolchainRegistry }}"
+    target_repo_template: "{{ .Values.targetRepoTemplate }}"
+    plugins:
+      {{- range .Values.plugins }}
+      - language: {{ .language }}
+        image: "{{ .image }}"
+      {{- end }}