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/plugin/cabi/loader.go

@@ -320,7 +320,7 @@ func go_core_dispatch(methodID C.int, ctx unsafe.Pointer, s1, s2, s3 *C.char, i1
 	case 3: // CORE_REGISTER_OUTPUT_CH
 		pid := pluginID
 		chName := a1
-		s.RegisterOutputChannel(chName, n1, a2, func(args map[string]interface{}) (interface{}, error) {
+		s.RegisterOutputChannel(chName, n1, a2, sdk.ChannelDef{}, func(args map[string]interface{}) (interface{}, error) {
 			// Output is async: return immediately, send in background
 			// to avoid nested cgo calls (cgo within cgo can crash)
 			go func() {