feat: connect conversations with Magic Notes

Let users retain useful assistant replies or complete conversations without
leaving their chat workflow. Preview and edit captured text, choose an existing
note or atomically create a note with its first entry, and return to the source
conversation or message from saved records.

Add an application-scoped Notes workbar tab with title/body search and quick
text appends. Preserve drafts across conversation switches and guard closing,
replacement and disabling. Schema 48 stores optional source metadata without
rewriting file-backed bodies; source deletion retains the saved note. Older
clients cannot reopen an upgraded database without a pre-upgrade backup.

Release note: 可将助手回答或完整会话预览、编辑后加入魔法笔记，并从笔记返回原会话或消息。右侧快速笔记支持搜索和追加文字，切换会话保留草稿；采集本身不调用模型，保存后自动评论仍遵循已有设置。

Validation: isolated HEAD-based candidate passed 22 files / 930 focused tests,
plus 20 gateway tests after including its create-result fixture adjustment.
Real Electron App/preload/IPC/SQLite acceptance passed for all 502 historical
messages, exact-entry/source navigation, native keyboard input in a 214px
panel, reopen and source-deletion retention, with zero capture model calls.
Repository lint and web TypeScript passed. Cached whitespace and secret-pattern
checks passed; native-client changes and unrelated IPC extraction are excluded.

Validation limits: the isolated source tree reuses installed node_modules,
where a parallel task upgraded DSH from the committed 0.1.2-rc.1 to 0.1.7-rc.2.
Full typecheck reports 14 DSH errors in three unchanged files; the full-suite
attempt with --bail=1 also fails in deepseek-harness-host.test.ts. These are not
all-green repository or release-package results. Earlier execution-time full
suite failures and fixture repairs remain recorded in the feature progress doc.

docs/features/assistant-workbar/README.md

@@ -1,6 +1,11 @@
 # 助手工作栏
 
-助手工作栏统一承载本机与远程执行空间、Task、成果、文件、浏览器和终端等持续工作界面。
+助手工作栏统一承载本机与远程执行空间、Task、成果、文件、浏览器、终端和笔记等持续工作界面。
+
+“笔记”为应用级、可关闭的单实例 Tab，新布局默认不打开。它提供搜索、浏览和快速追加文字，
+与主页面魔法笔记共用存储；会话采集、来源跳转与草稿规则由
+[魔法笔记文档](../magic-notes/README.md)维护。该应用已接入并通过真实 Electron 验收；
+全仓验证未全绿，聚焦复跑与执行时失败见[笔记验证进度](../magic-notes/progress.md)。
 
 ## 文档导航