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

toolchains/nodejs/Dockerfile

@@ -0,0 +1,17 @@
+FROM node:20-alpine
+
+ARG PROTOC_VERSION=25.1
+ARG PROTOC_GEN_TS_VERSION=1.8.2
+
+RUN apk add --no-cache git curl unzip
+
+RUN curl -sLO https://github.com/protocolbuffers/protobuf/releases/download/v${PROTOC_VERSION}/protoc-${PROTOC_VERSION}-linux-x86_64.zip && \
+    unzip -o protoc-${PROTOC_VERSION}-linux-x86_64.zip -d /usr/local && \
+    rm protoc-${PROTOC_VERSION}-linux-x86_64.zip
+
+RUN npm install -g protoc-gen-ts@${PROTOC_GEN_TS_VERSION}
+
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+ENTRYPOINT ["/entrypoint.sh"]