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/memory.go

@@ -2,12 +2,26 @@ package sdk
 
 import pubsdk "gitcode.com/JianFeeeee/homeagent-sdk/sdk"
 
-type MemoryAPI = pubsdk.MemoryAPI
+// MemoryAPI 是内置插件使用的全量图记忆接口。
+type MemoryAPI interface {
+	pubsdk.MemoryAPI
+	// GraphData 返回整个知识图谱的完整快照。
+	GraphData() (map[string]interface{}, error)
+}
+
 type Entity = pubsdk.Entity
 type Relation = pubsdk.Relation
 type Triple = pubsdk.Triple
 
-type TextMemoryAPI = pubsdk.TextMemoryAPI
+// TextMemoryAPI 是内置插件使用的全量文本记忆接口。
+type TextMemoryAPI interface {
+	pubsdk.TextMemoryAPI
+	// RecentEvents 返回最近 n 条记忆事件。
+	RecentEvents(n int) ([]TextEvent, error)
+	// Stats 返回文本记忆的运行统计。
+	Stats() map[string]interface{}
+}
+
 type TextEvent = pubsdk.TextEvent
 
 type DocMemoryAPI = pubsdk.DocMemoryAPI