feat(installer): M1 安装流程 + /setup 引导页

新增:
- installer/lock.go: lock 文件检测/创建/删除(原子写入);ErrLockExists sentinel
- installer/bootstrap.go: Detect() 启动期判定 ModeSetup/ModeNormal,
  损坏自愈(自动备份 db.corrupt-<ts> + 删 lock + 回退安装模式)
- middleware/installguard.go: 安装模式白名单(/setup /api/setup /health /metrics),
  中间件顺序: SecurityHeaders → InstallGuard → RateLimit → ...(避免限流计数污染)
- controller/setup.go: GET /api/setup/status + /api/setup/prefill + POST /api/setup;
  token 校验用常量时间比较防计时攻击;安装后端点永久 404
- router/setup.html: Vue3 + axios CDN,4 字段表单 + 动态音色行,
  调用 /api/setup/prefill 自动从旧 env 预填(API key 永不预填)

改造:
- main.go: 启动期 store.Open → installer.Detect → 注入 setup 控制器
- controller/tts.go: 安装模式双保险(/v1/audio/speech 即便漏过中间件也 503)
- controller/health.go (via dto): 加 installed + mode 字段,部署探针可识别
- router/router.go: 挂载 /setup + /api/setup/*,根路径安装模式跳 /setup
- setting/config.go: InitSetupToken 读 TTS_ADMIN_KEY 或随机生成 32 字符 hex
  (公网部署建议设 env;空时启动日志一次性打印)

删除:
- router/dashboard.go: 内容并入 router/router.go

.gitignore: tts.db / tts.db-* / installed.lock 加入(运行时产物)

验收(端到端跑通,见 scripts/ 已删除):
1. 删 lock → /v1/audio/speech 503 + /setup 200 HTML
2. POST /api/setup 错 token → 401;对 token → 200 + 写 lock + 写 db
3. 重复 POST → 404(端点永久关闭)
4. /health: 安装期 installed=false,装后 installed=true
5. 损坏 db header: 自动备份 tts.db.corrupt-<ts> + 删 lock + 回安装模式

测试:
- installer: 6 个 test, 覆盖 lock 生命周期 + Detect 三态 + 损坏自愈
- middleware: 3 个 test, 覆盖白名单/denylist/自定义
- store(M0): 仍 27/27 绿, 70.7% 覆盖率

二进制大小: 9.77 → 15.87 MB (+6MB,大部分是 setup.html embed + 新包)

controller/tts.go

@@ -14,6 +14,7 @@ import (
 	"github.com/volcano-tts/tts-api/adapter/volcano"
 	"github.com/volcano-tts/tts-api/common"
 	"github.com/volcano-tts/tts-api/dto"
+	"github.com/volcano-tts/tts-api/installer"
 	"github.com/volcano-tts/tts-api/metrics"
 	"github.com/volcano-tts/tts-api/middleware"
 	"github.com/volcano-tts/tts-api/setting"
@@ -62,6 +63,15 @@ func OpenaiTTSHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// 安装模式双保险:即使 InstallGuard 中间件没拦住,这里也 503 + 引导跳转
+	if installer.GetMode() == installer.ModeSetup {
+		log.Printf("[tts] 安装模式下拒绝 /v1/audio/speech - 客户端=%s", middleware.GetClientIP(r))
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.WriteHeader(http.StatusServiceUnavailable)
+		_, _ = w.Write([]byte(`{"error":"not installed","code":"install_required","redirect":"/setup"}`))
+		return
+	}
+
 	if !middleware.ValidateAPIKey(r) {
 		metrics.AuthFailed.Inc(telemetry.Labels{})
 		log.Printf("警告: API Key 鉴权失败 - 路径=%s 客户端=%s 远端=%s",
@@ -213,7 +223,12 @@ func contentTypeFor(format string) string {
 func HealthHandler(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
 
-	if setting.TTSConfigErr != nil {
+	// 安装模式下 /health 仍然 200,但通过 installed 字段让探针/运维识别
+	// (Kubernetes readiness probe 可以用 installed=false 决定是否放流量)
+	mode := installer.GetMode()
+	if mode == installer.ModeSetup {
+		w.WriteHeader(http.StatusOK) // 200,因为进程活着,只是还没初始化
+	} else if setting.TTSConfigErr != nil {
 		w.WriteHeader(http.StatusServiceUnavailable)
 	} else {
 		w.WriteHeader(http.StatusOK)
@@ -223,7 +238,9 @@ func HealthHandler(w http.ResponseWriter, r *http.Request) {
 	allRequired := env["all_required_vars_set"].(bool)
 
 	status := "ok"
-	if !allRequired {
+	if mode == installer.ModeSetup {
+		status = "not_installed"
+	} else if !allRequired {
 		status = "configuration_error"
 	}
 
@@ -239,6 +256,8 @@ func HealthHandler(w http.ResponseWriter, r *http.Request) {
 			AllRequiredVarsSet: allRequired,
 			ConfigError:        setting.TTSConfigErr != nil,
 		},
+		Installed: mode == installer.ModeNormal,
+		Mode:      mode.String(),
 	}
 	json.NewEncoder(w).Encode(resp)
 }