feat(wire): 地基④ wire.go 接 vision/voice/mcp/skill/exec 五个子系统，从死代码变可用

- vision：model.Router 绑 WithVisionModel(LLM_VISION_MODEL)；vision.RegisterTools(VisualTool/OCRTool)
  用同一 OpenAICompatibleAdapter（LLM_BASE_URL 为空则跳过并 Warn）。
- voice：voice.New(cfg.Voice) Chain（cloud→local→edge-tts/espeak→silent）存 a.voice。
- mcp：读 cfg.MCP.ServersJSON → 逐 Enabled server mcp.NewRegistry(...).Register(ctx)（Connect+
  DiscoverTools+RegisterTool），注册 KindMCP 能力 mcp:<name> 供 adminListPlugins 枚举；
  close() 中 Unregister 防 stdio 子进程孤儿；每 server 15s connect 超时，失败 Warn 跳过。
- skills：LoadDir(configs/skills) → skills.Register 为 KindSkill（Runner.Run 仍 ErrRunPending，
  执行留后续）。
- exec/terminal：新 terminalTool(sdk.Tool) 内部调 execProv.Execute，注册进 dispatcher；
  ExecSandbox.Enabled=false 默认拦截（授权默认关）。
- config：LLMConfig 增 VisionModel(LLM_VISION_MODEL)；新增 MCPConfig/ServersJSON(MCPSERVERS_JSON)。
- 拆 5 个辅助文件（vision.go/voice.go/mcp.go/skills.go/terminal_tool.go）避免 wire.go 膨胀；
  wire.go 最终 535 行。

默认配置下各子系统干净跳过不阻断启动（LLM_BASE_URL 已配则 vision 用主模型降级）。
go build/vet/test 全绿（46 包），gofmt 干净。

internal/config/config.go

@@ -31,6 +31,7 @@ type Config struct {
 	Background  BackgroundConfig
 	WSHub       WSHubConfig
 	ExecSandbox ExecSandbox
+	MCP         MCPConfig
 }
 
 // ServerConfig holds the single gateway listener settings.
@@ -69,6 +70,10 @@ type LLMConfig struct {
 	Model    string `env:"LLM_MODEL"`
 	Fallback string `env:"LLM_FALLBACK_MODEL"`
 
+	// VisionModel is the dedicated model used for image/vision requests. When
+	// set, the model router routes image content to it (see model.Router.WithVisionModel).
+	VisionModel string `env:"LLM_VISION_MODEL"`
+
 	// Anthropic native provider, used when Provider=anthropic. Independent
 	// config block so each vendor is a self-contained config.
 	AnthropicBaseURL  string `env:"ANTHROPIC_BASE_URL"`
@@ -110,6 +115,24 @@ type WSHubConfig struct {
 	SessionIdleTimeout int `env:"SESSION_IDLE_TIMEOUT_MIN" default:"30"`
 }
 
+// MCPConfig holds Model Context Protocol server settings. The reflection-based
+// loader only supports scalars and []string, so servers are supplied as a JSON
+// array string (ServersJSON, env MCP_SERVERS_JSON) and parsed at startup by the
+// MCP wiring (cmd/cyrene/mcp.go).
+type MCPConfig struct {
+	ServersJSON string `env:"MCP_SERVERS_JSON"`
+}
+
+// MCPServer describes a single MCP server: a stdio subprocess (Command/Args) or
+// an SSE endpoint (URL). Enabled gates activation at startup.
+type MCPServer struct {
+	Name    string   `json:"name"`
+	Command string   `json:"command"`
+	Args    []string `json:"args"`
+	URL     string   `json:"url"`
+	Enabled bool     `json:"enabled"`
+}
+
 // Load reads configuration, merging an optional .env file (development only)
 // with process environment variables. Process environment variables always take
 // precedence over .env values, which take precedence over code defaults.