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/events.go

@@ -0,0 +1,20 @@
+package sdk
+
+import "gitcode.com/JianFeeeee/HomeAgent/internal/events"
+
+// 事件类型/事件类型别名：插件经 SDK 订阅/发布内核事件，
+// 无需直接 import internal/events（内核事件总线仅通过 SDK 暴露）。
+
+type EventType = events.EventType
+type Event = events.Event
+
+const (
+	EventRawInput       = events.EventRawInput
+	EventAgentOutput    = events.EventAgentOutput
+	EventAgentLLMChain  = events.EventAgentLLMChain
+	EventToolCall       = events.EventToolCall
+	EventReasoning      = events.EventReasoning
+	EventStage          = events.EventStage
+	EventSystem         = events.EventSystem
+	EventAll            = events.EventAll
+)