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/kol_manage_handler.go

@@ -42,7 +42,7 @@ func NewKolManageHandler(a *bootstrap.App, assets *AssetHandler) *KolManageHandl
 		profileSvc: profileSvc,
 		pkgSvc:     app.NewKolPackageService(profileSvc, a.KolPackages, a.KolPrompts, a.KolSubscriptions).WithCache(a.Cache),
 		promptSvc:  app.NewKolPromptService(a.DB, profileSvc, a.KolPackages, a.KolPrompts, a.KolSubscriptions, a.KolPromptAsset).WithCache(a.Cache),
-		assistSvc:  app.NewKolAssistService(a.DB, profileSvc, a.KolAssists, a.LLM, a.RabbitMQ, a.Config.LLM, a.Logger).WithCache(a.Cache),
+		assistSvc:  app.NewKolAssistService(a.DB, profileSvc, a.KolAssists, a.LLM, a.RabbitMQ, a.Config().LLM, a.Logger).WithCache(a.Cache).WithConfigProvider(a.ConfigStore),
 		assets:     assets,
 	}
 }