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

.gitignore

@@ -21,3 +21,11 @@ login.json
 cmd/gui/node_modules/
 cmd/gui/dist/
 
+.gopath/
+
+# SDK 工具链 — 核心仓不追踪
+third_party/homeagent-sdk/bin/
+third_party/homeagent-sdk/tools/
+third_party/homeagent-sdk/package/
+third_party/homeagent-sdk/.gitignore
+third_party/homeagent-sdk/README*