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/app/knowledge_url_parser.go

@@ -77,7 +77,8 @@ func (s *KnowledgeService) parseWebsiteKnowledge(ctx context.Context, rawURL str
 }
 
 func (s *KnowledgeService) executeLinkReader(ctx context.Context, rawURL string) (*arkWebDataItem, error) {
-	baseURL := strings.TrimRight(strings.TrimSpace(s.arkBaseURL), "/")
+	runtimeCfg := s.runtimeConfig()
+	baseURL := strings.TrimRight(strings.TrimSpace(runtimeCfg.ArkBaseURL), "/")
 	if baseURL == "" {
 		baseURL = defaultKnowledgeArkBaseURL
 	}
@@ -102,7 +103,7 @@ func (s *KnowledgeService) executeLinkReader(ctx context.Context, rawURL string)
 	if err != nil {
 		return nil, fmt.Errorf("create webpage parser request: %w", err)
 	}
-	req.Header.Set("Authorization", "Bearer "+s.arkAPIKey)
+	req.Header.Set("Authorization", "Bearer "+runtimeCfg.ArkAPIKey)
 	req.Header.Set("Content-Type", "application/json")
 
 	resp, err := s.httpClient.Do(req)
@@ -146,9 +147,10 @@ func (s *KnowledgeService) formatWebsiteMarkdown(ctx context.Context, title, con
 	}
 
 	sections := make([]string, 0, len(chunks)+1)
+	runtimeCfg := s.runtimeConfig()
 	for index, chunk := range chunks {
 		result, err := s.llmClient.Generate(ctx, llm.GenerateRequest{
-			Model:           s.urlMarkdownModel,
+			Model:           runtimeCfg.URLMarkdownModel,
 			Prompt:          prompts.KnowledgeWebsiteMarkdownPrompt(title, rawURL, chunk, index, len(chunks)),
 			Timeout:         defaultKnowledgeURLMarkdownTimeout,
 			MaxOutputTokens: defaultKnowledgeURLMarkdownOutputToken,