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/indexer_impl.go

@@ -0,0 +1,71 @@
+package sdk
+
+import (
+	"errors"
+
+	"gitcode.com/JianFeeeee/HomeAgent/internal/memory"
+)
+
+// indexerImpl 桥接 memory.Indexer 到中立的 IndexerAPI。
+type indexerImpl struct {
+	idx *memory.Indexer
+}
+
+func NewIndexer(idx *memory.Indexer) IndexerAPI {
+	return &indexerImpl{idx: idx}
+}
+
+func (i *indexerImpl) BuildContext(q string) (*IndexContext, error) {
+	if i.idx == nil {
+		return nil, errors.New("indexer not available")
+	}
+	ctx := i.idx.BuildContext(q)
+	if ctx == nil {
+		return &IndexContext{}, nil
+	}
+	entities := make([]Entity, len(ctx.Entities))
+	for j, e := range ctx.Entities {
+		entities[j] = Entity{Name: e.Name, Type: e.Type, MentionCount: e.MentionCount}
+	}
+	relations := make([]Relation, len(ctx.Relations))
+	for j, r := range ctx.Relations {
+		relations[j] = Relation{SourceName: r.SourceName, TargetName: r.TargetName, RelationType: r.RelationType}
+	}
+	return &IndexContext{
+		Entities:      entities,
+		Relations:     relations,
+		Summary:       ctx.Summary,
+		TokenEstimate: ctx.TokenEstimate,
+	}, nil
+}
+
+func (i *indexerImpl) FormatContext(ctx *IndexContext) string {
+	if i.idx == nil || ctx == nil {
+		return ""
+	}
+	entities := make([]memory.Entity, len(ctx.Entities))
+	for j, e := range ctx.Entities {
+		entities[j] = memory.Entity{Name: e.Name, Type: e.Type, MentionCount: e.MentionCount}
+	}
+	return i.idx.FormatContext(&memory.InjectedContext{
+		Entities:      entities,
+		Summary:       ctx.Summary,
+		TokenEstimate: ctx.TokenEstimate,
+	})
+}
+
+func (i *indexerImpl) GetToolDefinitions() []map[string]interface{} {
+	if i.idx == nil {
+		return nil
+	}
+	return i.idx.GetToolDefinitions()
+}
+
+func (i *indexerImpl) BuildToolPrompt() string {
+	if i.idx == nil {
+		return ""
+	}
+	return i.idx.BuildToolPrompt()
+}
+
+var _ IndexerAPI = (*indexerImpl)(nil)