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/skill/manager.go

@@ -8,18 +8,12 @@ import (
 	"sort"
 	"strings"
 	"sync"
+
+	sdk "gitcode.com/JianFeeeee/HomeAgent/internal/sdk"
 )
 
-type Skill struct {
-	Name        string `json:"name"`
-	Description string `json:"description"`
-	Version     string `json:"version"`
-	Author      string `json:"author,omitempty"`
-	Entry       string `json:"entry,omitempty"`
-	Source      string `json:"source,omitempty"`
-	Enabled     bool   `json:"enabled"`
-	RawContent  string `json:"-"`
-}
+// Skill 已迁入内置 SDK，此处保留别名以兼容现有调用方。
+type Skill = sdk.Skill
 
 type Manager struct {
 	mu          sync.RWMutex
@@ -195,6 +189,9 @@ func (m *Manager) GetInjectedPrompt() string {
 	return strings.Join(parts, "\n\n")
 }
 
+// Manager 直接满足内置 SDK 的 SkillAPI（复用优先，无需独立适配器）。
+var _ sdk.SkillAPI = (*Manager)(nil)
+
 func extractDescription(content string) string {
 	lines := strings.Split(content, "\n")
 	for _, line := range lines {