refactor: migrate built-in plugins to SDK-only interface

- Six-phase plan complete: webui/cli/healthcheck/pluginmgr/clawhubadapter
  now interact with the kernel exclusively via internal/sdk interfaces;
  all Configure() calls and package-level global injection removed
- buildSDK in internal/plugin/registry.go is the single assembly point
- Add internal/sdk/events.go exporting event types/constants
- Fix ProviderManager cooldown sharing: LuaAdaptedProvider.Name() now
  returns the source name instead of lua_<adapter>, so multiple sources
  sharing an adapter (single script load via shared VM AdapterCache) no
  longer share failure-cooldown state
- Verified: build/vet/tests green, deployed to homeagent.service with
  full plugin capability testing via local OpenAI-compatible mock

internal/agent/api/provider.go

@@ -211,7 +211,7 @@ type LuaAdaptedProvider struct {
 	client  *http.Client
 }
 
-func NewLuaAdaptedProvider(cfg BaseConfig, vm *luaVM.VM, adapter string) *LuaAdaptedProvider {
+func NewLuaAdaptedProvider(cfg BaseConfig, vm *luaVM.VM, name, adapter string) *LuaAdaptedProvider {
 	if cfg.Temperature == 0 {
 		cfg.Temperature = 0.7
 	}
@@ -219,7 +219,7 @@ func NewLuaAdaptedProvider(cfg BaseConfig, vm *luaVM.VM, adapter string) *LuaAda
 		cfg.MaxTokens = 4096
 	}
 	return &LuaAdaptedProvider{
-		name:    fmt.Sprintf("lua_%s", adapter),
+		name:    name,
 		cfg:     cfg,
 		vm:      vm,
 		adapter: adapter,

internal/agent/api/quickchat_test.go

@@ -28,7 +28,7 @@ func TestQuickChatWithRealKey(t *testing.T) {
 		Model:   "deepseek-v4-flash",
 		BaseURL: "https://api.deepseek.com",
 		APIKey:  apiKey,
-	}, vm, "deepseek"))
+	}, vm, "deepseek", "deepseek"))
 
 	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 	defer cancel()