feat(server): hot-reload config store and reloadable infra clients

- Replace single Load() with a watching Store that re-reads config files
  (and config.local.yaml) and fans out a ReloadEvent with a per-field diff
  so consumers can decide whether the change is hot-applicable or requires
  a process restart.
- Wrap llm, retrieval, vector store, and object storage clients in
  Reloadable* shells so the bootstrap can swap their underlying impls when
  config changes without re-instantiating handlers.
- Make jwt.Manager and ops TokenIssuer mutable under a lock so secrets and
  TTLs can be rotated live; thread default plan code through a setter on
  the ops AdminUserService.
- Wire ConfigStore through bootstrap and every cmd/main.go, scheduler /
  worker / tenant-api / ops-api start the watcher; services and handlers
  take a config.Provider so they always read current values for things
  like generation.stream_enabled, scheduler dispatch, retrieval, etc.
- Switch shared/config decoding off viper to a Kratos-derived runtime
  package so env placeholders (\${VAR:default}) resolve consistently and
  the same source machinery powers both the loader and the watcher.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/tenant/transport/internal_metrics_handler.go

@@ -11,14 +11,14 @@ import (
 )
 
 func registerInternalMetricsRoutes(app *bootstrap.App) {
-	token := strings.TrimSpace(app.Config.Scheduler.InternalMetricsToken)
+	token := strings.TrimSpace(app.Config().Scheduler.InternalMetricsToken)
 	if token == "" {
 		app.Logger.Warn("tenant-api internal metrics routes not registered: scheduler.internal_metrics_token is required")
 		return
 	}
 
 	metrics := app.Engine.Group("/api/internal/metrics")
-	metrics.Use(internalMetricsAuthMiddleware(token))
+	metrics.Use(internalMetricsAuthMiddleware(app))
 	metrics.GET("/monitoring/heartbeat-primary-lease", func(c *gin.Context) {
 		response.Success(c, tenantapp.MonitoringHeartbeatPrimaryLeaseMetricsSnapshotValue())
 	})
@@ -35,9 +35,12 @@ func registerInternalMetricsRoutes(app *bootstrap.App) {
 	})
 }
 
-func internalMetricsAuthMiddleware(token string) gin.HandlerFunc {
-	expected := strings.TrimSpace(token)
+func internalMetricsAuthMiddleware(app *bootstrap.App) gin.HandlerFunc {
 	return func(c *gin.Context) {
+		expected := ""
+		if cfg := app.Config(); cfg != nil {
+			expected = strings.TrimSpace(cfg.Scheduler.InternalMetricsToken)
+		}
 		if expected == "" || !internalMetricsTokenMatches(c, expected) {
 			response.Error(c, response.ErrUnauthorized(40181, "internal_metrics_unauthorized", "valid internal metrics token is required"))
 			c.Abort()