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

internal/api/server.go

@@ -0,0 +1,58 @@
+package api
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+
+	"proto-gen/internal/config"
+	"proto-gen/internal/database"
+	"proto-gen/internal/gitclient"
+)
+
+type Server struct {
+	router *chi.Mux
+	db     *database.DB
+	cfg    *config.Config
+	git    gitclient.GitClient
+}
+
+func NewServer(db *database.DB, cfg *config.Config, git gitclient.GitClient) *Server {
+	s := &Server{
+		router: chi.NewRouter(),
+		db:     db,
+		cfg:    cfg,
+		git:    git,
+	}
+	s.routes()
+	return s
+}
+
+func (s *Server) routes() {
+	s.router.Use(middleware.Logger)
+	s.router.Use(middleware.Recoverer)
+	s.router.Use(middleware.Compress(5))
+
+	s.router.Route("/api/v1", func(r chi.Router) {
+		r.Post("/tasks", s.handleCreateTask)
+		r.Get("/tasks", s.handleListTasks)
+		r.Get("/tasks/{id}", s.handleGetTask)
+		r.Post("/tasks/{id}/retry", s.handleRetryTask)
+		r.Get("/plugins", s.handleListPlugins)
+		r.Get("/plugins/{lang}/versions", s.handleGetPluginVersion)
+		r.Put("/plugins/{lang}/versions", s.handleUpdatePluginVersion)
+	})
+
+	s.router.Handle("/*", http.FileServer(http.Dir("internal/static")))
+}
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	s.router.ServeHTTP(w, r)
+}
+
+func (s *Server) Start(addr string) error {
+	log.Printf("server listening on %s", addr)
+	return http.ListenAndServe(addr, s.router)
+}