refactor: P0-P3 fixes, C1 cleanup, architecture diagrams, go.work upgrade

- P0-1: ProviderError type + ReportStatus for precise 401/403 detection
- P0-2: Remove -config flag from deploy/homeagent.service
- P2-1: 5s debounce on context.go Save()
- P2-2→C1: Delete output_set_channel entirely
- P2-3: Extract mediaDataURL/mediaChat helpers
- P2-4: Dedup defaultSources var
- P3: Delete dead packages (embed/tokenizer/container/snapshot)
- P3: Delete dead functions (messagesToMap, RunStageAll)
- CL: Update .gitignore, docs, Makefile, gojieba removal
- Config: Delete config/config.yaml, update docs
- Arch: Remove EmitOutputTo from emitResponse
- CL-1: go.work 1.19→1.21
- Docs: Add Mermaid architecture diagrams to README
- Docs: Add kernel-rebuild requires plugin-rebuild note to PLUGIN_DEV.md

docs/OVERVIEW.md

@@ -48,7 +48,7 @@ HomeAgent 是一个持续运行的个人智能 Agent 框架。
 **插件系统** (`internal/plugin/`)：
 - 内置插件：Go `init()` 自注册，编译进内核
 - 外部插件：Go `-buildmode=plugin` 编译为 `.so`，通过 `plugin.Open` 动态加载
-- PluginSDK (`internal/plugin/sdk/`) 定义三通道：RegisterTool / RegisterStage / Subscribe
+- PluginSDK (`internal/sdk/`) 定义三通道：RegisterTool / RegisterStage / Subscribe
 - 阶段钩子 7 个：on_input → pre_action → post_action → before_toolcall → after_toolcall → before_output → after_output
 
 **LLM Provider** (`internal/agent/api/provider.go`)：
@@ -68,5 +68,5 @@ HomeAgent 是一个持续运行的个人智能 Agent 框架。
 核心功能已可运行。插件系统和 SDK 已就绪，可独立开发外部插件。
 
 - 内置插件：webui / cli / timer / cmd / mcp / agentcli / healthcheck / pluginmgr / openclaw / files
-- 外部插件示例（SDK 仓库 `example/`）：qq / files / web / memo
+- 外部插件示例（[homeagent-sdk](https://gitcode.com/JianFeeeee/homeagent-sdk) 仓库 `example/`）：qq / files / web / memo / bili / editdoc / a2a / ocr
 - 打包分发：`.hmap` 插件包格式，通过 WebUI 安装