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/supervisor.go

@@ -0,0 +1,25 @@
+package sdk
+
+import (
+	"time"
+
+	"gitcode.com/JianFeeeee/HomeAgent/pkg/types"
+)
+
+// SupervisorAPI provides access to agent lifecycle management.
+type SupervisorAPI interface {
+	ListAgents() []AgentStatus
+	GetAgentStatus(id string) (*AgentStatus, error)
+	PreActionSnapshot(id string) (*types.Snapshot, error)
+	RollbackAgent(id string, snapID string) error
+}
+
+// AgentStatus is a neutral snapshot of a supervised agent.
+type AgentStatus struct {
+	ID           types.AgentID             `json:"id"`
+	State        types.AgentState          `json:"state"`
+	Health       types.HealthStatus        `json:"health"`
+	Uptime       time.Duration             `json:"uptime,omitempty"`
+	Network      types.NetworkCheckResult  `json:"network,omitempty"`
+	TrackerStats map[string]interface{}    `json:"tracker_stats,omitempty"`
+}