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/sdk/config_impl.go

@@ -0,0 +1,22 @@
+package sdk
+
+import "gitcode.com/JianFeeeee/HomeAgent/pkg/types"
+
+// configImpl 持有运行期配置对象的引用（与配置数据库无关）。
+type configImpl struct {
+	cfg *types.Config
+}
+
+func NewConfig(cfg *types.Config) ConfigAPI {
+	return &configImpl{cfg: cfg}
+}
+
+func (c *configImpl) Get() *types.Config {
+	return c.cfg
+}
+
+func (c *configImpl) Put(cfg *types.Config) {
+	c.cfg = cfg
+}
+
+var _ ConfigAPI = (*configImpl)(nil)