feat: implement streaming chat, skill routing, and SAFe PI planning tools

- Add /api/chat/stream endpoint with Server-Sent Events (SSE) for real-time message streaming
  * Implement StreamEvent types (thought, tool_call, tool_result, final, error)
  * Add StreamEventCallback mechanism for event propagation
  * Create StreamChatHandler in webui/bot with proper HTTP headers and flushing

- Implement LLM-based skill router for intelligent capability selection
  * Add optional routerLLM client for semantic routing
  * Implement routeSkillsWithLLM() to match user intent to available skills
  * Add matchSkillsByName() for fuzzy skill matching
  * Update buildUnifiedSystemPrompt() to use routed skills

- Add streaming support to ReAct pipeline
  * Implement runUnifiedReActStream() for streaming thought/action/observation
  * Emit StreamEvent at each ReAct step
  * Support callback error handling in streaming mode

- Integrate three new DevOps tools
  * tools/filedoc: Extract document content from file_id via OpenAI
  * tools/giteaticket: Create Gitea issues from PI plan items with SAFe metadata
  * tools/piplan: Publish PI planning blueprints with dependency tracking

- Add SAFe PI Planning skill
  * Implement PM/SA/RTE (iron triangle) workflow
  * Support for Feature, Enabler, and Dependency definition
  * Automatic task decomposition and Gitea integration

- Create frontend integration documentation
  * Complete SSE protocol specification
  * TypeScript fetch + ReadableStream example
  * LLM-ready refactoring template for other projects

- Simplify file handling
  * Remove legacy file context structures and dual-mode processing
  * Consolidate file operations into UploadAndCacheFiles()
  * Remove FilePromptMode configuration and related complexity

- Update configuration
  * Add Router model support (LLM_ROUTER_MODEL)
  * Add Gitea configuration (BaseURL, Token, Owner, Repo)
  * WebSearch and additional tool infrastructure

Tests: All 22 test packages passing, 8/8 webui tests including 3 new stream tests

internal/config/config.go

@@ -29,6 +29,7 @@ type Config struct {
 	LLM       LLMConfig
 	Security  SecurityConfig
 	WebSearch WebSearchConfig
+	Gitea     GiteaConfig
 
 	SQLitePath string
 }
@@ -52,11 +53,11 @@ type WebUIConfig struct {
 }
 
 type LLMConfig struct {
-	BaseURL        string
-	APIKey         string
-	Model          string
-	FileModel      string
-	FilePromptMode string
+	BaseURL     string
+	APIKey      string
+	Model       string
+	FileModel   string
+	RouterModel string // 轻量路由模型，用于技能意图路由；为空则仅用关键词匹配
 }
 
 type SecurityConfig struct {
@@ -70,6 +71,13 @@ type WebSearchConfig struct {
 	APIKey string
 }
 
+type GiteaConfig struct {
+	BaseURL string // Gitea 实例地址
+	Token   string // Personal Access Token
+	Owner   string // 仓库所有者
+	Repo    string // 仓库名称
+}
+
 func Load() (Config, error) {
 	agentWorkspaceDir := resolveAgentWorkspaceDir()
 	if err := preloadEnvFiles(); err != nil {
@@ -106,11 +114,11 @@ func Load() (Config, error) {
 			MaxUploadBytes: int64(intFromEnv("WEBUI_MAX_UPLOAD_MB", 20)) * 1024 * 1024,
 		},
 		LLM: LLMConfig{
-			BaseURL:        strings.TrimRight(defaultIfEmpty(os.Getenv("LLM_BASE_URL"), "https://api.openai.com/v1"), "/"),
-			APIKey:         strings.TrimSpace(os.Getenv("LLM_API_KEY")),
-			Model:          defaultIfEmpty(os.Getenv("LLM_MODEL"), "gpt-4o-mini"),
-			FileModel:      defaultIfEmpty(os.Getenv("LLM_FILE_MODEL"), defaultIfEmpty(os.Getenv("LLM_MODEL"), "gpt-4o-mini")),
-			FilePromptMode: normalizeFilePromptMode(defaultIfEmpty(os.Getenv("LLM_FILE_PROMPT_MODE"), "user_content_file_parts")),
+			BaseURL:     strings.TrimRight(defaultIfEmpty(os.Getenv("LLM_BASE_URL"), "https://api.openai.com/v1"), "/"),
+			APIKey:      strings.TrimSpace(os.Getenv("LLM_API_KEY")),
+			Model:       defaultIfEmpty(os.Getenv("LLM_MODEL"), "gpt-4o-mini"),
+			FileModel:   defaultIfEmpty(os.Getenv("LLM_FILE_MODEL"), defaultIfEmpty(os.Getenv("LLM_MODEL"), "gpt-4o-mini")),
+			RouterModel: strings.TrimSpace(os.Getenv("LLM_ROUTER_MODEL")),
 		},
 		SQLitePath: defaultIfEmpty(os.Getenv("SQLITE_PATH"), filepath.Join(defaultDataDir, "laodingbot.db")),
 		WebSearch: WebSearchConfig{
@@ -122,6 +130,12 @@ func Load() (Config, error) {
 			AllowedCommands: splitCSV(defaultIfEmpty(os.Getenv("ALLOWED_COMMANDS"), "pwd,ls,cat,echo,grep,find,head,tail,go")),
 			WorkDir:         defaultIfEmpty(os.Getenv("WORK_DIR"), defaultWorkSubdir),
 		},
+		Gitea: GiteaConfig{
+			BaseURL: strings.TrimRight(strings.TrimSpace(os.Getenv("GITEA_BASE_URL")), "/"),
+			Token:   strings.TrimSpace(os.Getenv("GITEA_TOKEN")),
+			Owner:   strings.TrimSpace(os.Getenv("GITEA_OWNER")),
+			Repo:    strings.TrimSpace(os.Getenv("GITEA_REPO")),
+		},
 	}
 
 	cfg.MessageChannel = strings.ToLower(strings.TrimSpace(cfg.MessageChannel))
@@ -178,9 +192,6 @@ func Load() (Config, error) {
 	if cfg.LLM.APIKey == "" {
 		return Config{}, fmt.Errorf("LLM_API_KEY is required")
 	}
-	if cfg.LLM.FilePromptMode != "user_content_file_parts" && cfg.LLM.FilePromptMode != "system_fileid_uri" {
-		return Config{}, fmt.Errorf("LLM_FILE_PROMPT_MODE must be one of: user_content_file_parts, system_fileid_uri")
-	}
 
 	cfg.SoulPath = resolvePathInWorkspace(cfg.SoulPath, agentWorkspaceDir)
 	cfg.SkillsDir = resolvePathInWorkspace(cfg.SkillsDir, agentWorkspaceDir)
@@ -417,14 +428,3 @@ func splitCSV(raw string) []string {
 	}
 	return out
 }
-
-func normalizeFilePromptMode(v string) string {
-	v = strings.ToLower(strings.TrimSpace(v))
-	if v == "" {
-		return "user_content_file_parts"
-	}
-	if v == "system_fileid" || v == "system_fileid_url" || v == "system_fileid_uri" {
-		return "system_fileid_uri"
-	}
-	return v
-}