sdk: embed non-toolchain SDK in third_party, add NoMemory/Cleaner support

- Embed sdk/, example/, meta/, go.mod from homeagent-sdk (no .git)
- Core .gitignore excludes SDK toolchain: bin/, tools/, package/
- RegisterInputChannel + ChannelDef(NoMemory, Cleaner) in SDK
- IOManager input channel registry with GetInputChannelDef
- eventloop: apply channel Cleaner/NoMemory to interrupt text
- context engine: channelDefLookup applied in textForVector
- document store: ChannelCleaner param for archive functions
- All callers/adapters updated with ChannelDef{} default

internal/sdk/plugin.go

@@ -48,6 +48,8 @@ const (
 )
 type APIRegistrar = pubsdk.APIRegistrar
 type OutputChannelRegistrar = pubsdk.OutputChannelRegistrar
+type InputChannelRegistrar = pubsdk.InputChannelRegistrar
+type ChannelDef = pubsdk.ChannelDef
 
 type PluginSDK struct {
 	*pubsdk.PluginSDK
@@ -92,6 +94,7 @@ type SDKConfig struct {
 	RegStage   StageRegistrar
 	RegAPI     APIRegistrar
 	RegOutput  OutputChannelRegistrar
+	RegInput   InputChannelRegistrar
 }
 
 func New(name string, cfg SDKConfig) *PluginSDK {
@@ -99,6 +102,9 @@ func New(name string, cfg SDKConfig) *PluginSDK {
 	if cfg.IOManager != nil {
 		base.SetIOInjector(ioAdapter{iom: cfg.IOManager})
 	}
+	if cfg.RegInput != nil {
+		base.SetInputChannelRegistrar(cfg.RegInput)
+	}
 	base.SetMemoryAPI(cfg.Memory)
 	base.SetTextMemoryAPI(cfg.TextMemory)
 	base.SetDocMemoryAPI(cfg.DocMemory)