feat: add persistent document handling and protect note drafts

Add HTTP PaddleOCR-VL settings and shared document previews for chat and knowledge imports. Preserve attachment originals and parsed assets across drafts, messages and queues; support explicit image OCR, selecting document images into a conversation draft, and restoring queued input for editing.

Protect unsaved note bodies and titles during navigation and asynchronous updates. Match canvas analysis to source revisions, invalidate affected comments, preserve annotations during pagination, and provide a resizable record index with saved width preferences.

Existing OCR settings retain local behavior. Historical attachments without saved originals are not reconstructed. Advanced OCR options depend on the configured service; image sending depends on the effective model and Runtime.

Validation: full typecheck and lint passed; 477 focused tests passed across 12 files; staged whitespace checks passed. The full repository suite was not rerun for this commit.

Release note: Keep note drafts safe while switching workspaces, resize the record index, and revisit saved document attachments with OCR previews and selected images in chat.

docs/features/application-tool-navigation/README.md

@@ -117,3 +117,4 @@ Notion 收藏和 VS Code Profiles，当前版本已移除场景工具包与快
 - [助手工作栏多终端页签 PRD](../assistant-workbar/terminal-tabs-prd.md)
 - [智能心跳 PRD](../smart-heartbeat/prd.md)
 - [知识库功能文档](../knowledge-base/README.md)
+- [文档解析入口与职责](../document-processing/ui-design.md#11-入口与职责)：全局 OCR 配置、附件与知识文档操作的目标分工；不新增应用中心成员，本机推理监控不管理 HTTP OCR 服务。

docs/features/application-tool-navigation/ui-design.md

@@ -270,6 +270,10 @@ Modal 与真实执行模块已接入；支持清单及验证范围分别见技
 
 服务列表提供首次加载、无服务、加载失败重试及保留旧快照的刷新失败状态；刷新期间或失败时禁用服务操作。
 OCR 忙碌或模型不可用时禁用加载与释放，并在执行模块再次检查。
+文档解析与 HTTP OCR 的配置归属见[文档处理入口设计](../document-processing/ui-design.md#11-入口与职责)，
+不因接入 HTTP 而扩展本机服务列表。“模型与连接设置”现直达 `model`，OCR 服务行的
+“文档解析设置”直达 `document-parsing`，关闭设置返回原工作区；实施与验证见
+[文档处理进度](../document-processing/progress.md#2026-09-19-实现与验证)。
 页面不显示无来源的进度条或资源数值。US-B6 至 US-B9 的应用中心、顺序、启用联动、笔记共同设置映射见
 [需求对应](./logic-design.md#6-与需求的对应关系)。