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/worker/scheduler_test.go

@@ -0,0 +1,53 @@
+package worker
+
+import (
+	"testing"
+	"time"
+
+	"proto-gen/internal/config"
+	"proto-gen/internal/database"
+	"proto-gen/internal/k8s"
+)
+
+func newTestScheduler(t *testing.T) (*Scheduler, *database.DB) {
+	t.Helper()
+	db, err := database.New(t.TempDir() + "/test.db")
+	if err != nil {
+		t.Fatalf("creating db: %v", err)
+	}
+	t.Cleanup(func() { db.Close() })
+
+	cfg := &config.Config{
+		Cluster: config.ClusterConfig{
+			Namespace:     "test",
+			JobTimeout:    300,
+			MaxConcurrent: 2,
+		},
+		ToolchainRegistry: "registry.example.com",
+	}
+
+	k8sClient := k8s.NewClientFromInterface(nil)
+	scheduler := NewScheduler(db, k8sClient, cfg)
+	scheduler.pollInterval = 100 * time.Millisecond
+
+	return scheduler, db
+}
+
+func TestNewScheduler(t *testing.T) {
+	scheduler, db := newTestScheduler(t)
+	defer db.Close()
+
+	if scheduler.db == nil {
+		t.Error("db is nil")
+	}
+	if scheduler.k8sClient == nil {
+		t.Error("k8sClient is nil")
+	}
+}
+
+func TestProcessPendingTasks_Empty(t *testing.T) {
+	scheduler, db := newTestScheduler(t)
+	defer db.Close()
+
+	scheduler.processPendingTasks()
+}