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/models/models.go

@@ -0,0 +1,37 @@
+package models
+
+import "time"
+
+type TaskStatus string
+
+const (
+	StatusPending TaskStatus = "pending"
+	StatusRunning TaskStatus = "running"
+	StatusSuccess TaskStatus = "success"
+	StatusFailed  TaskStatus = "failed"
+)
+
+type Task struct {
+	ID             string     `json:"id"`
+	Status         TaskStatus `json:"status"`
+	Language       string     `json:"language"`
+	ProtoRepo      string     `json:"proto_repo"`
+	ProtoBranch    string     `json:"proto_branch"`
+	ProtoCommit    string     `json:"proto_commit,omitempty"`
+	TargetRepo     string     `json:"target_repo"`
+	ToolchainImage string     `json:"toolchain_image"`
+	ImageDigest    string     `json:"image_digest,omitempty"`
+	ResultCommit   string     `json:"result_commit,omitempty"`
+	Error          string     `json:"error,omitempty"`
+	Log            string     `json:"log,omitempty"`
+	Retries        int        `json:"retries"`
+	CreatedAt      time.Time  `json:"created_at"`
+	UpdatedAt      time.Time  `json:"updated_at"`
+}
+
+type ToolchainVersion struct {
+	Language  string    `json:"language"`
+	ImageTag  string    `json:"image_tag"`
+	Enabled   bool      `json:"enabled"`
+	UpdatedAt time.Time `json:"updated_at"`
+}