feat: add evidence search and stabilize pdf previews

- add document evidence parsing/search/open routes, Hermes tool wiring, local index settings/status, and the document-evidence skill plus design notes
- fix PDF resource tabs by rendering PDFs inline with pdf.js canvases instead of iframe preview pages, release PDF documents on close, and document the fourth-PDF stall bug
- keep PDF preview at 2x rendering while removing the previous lazy-load/placeholder direction, and make dev:hot bind loopback defaults externally reachable

Verification:
- node --check rust/crates/mnote-web/browser/document-resource-tab-runtime.js
- node scripts/task-dev-hot-plan-test.js
- cargo test -p mnote-web --manifest-path rust/Cargo.toml pdf_preview_page_does_not_render_visible_toolbar
- cargo test -p mnote-web --manifest-path rust/Cargo.toml document_shell_returns_page_aggregate_snapshot
- cargo build -p mnote-web --manifest-path rust/Cargo.toml
- browser smoke: sequentially opened the four tea_seed_oil_cosmetic PDFs; fourth PDF rendered 15/15 canvases, iframeCount=0, browser errors=0

design/10-review/done/17-sidex-mnote-workbench-gap-execution-checklist-v1.md

@@ -190,7 +190,7 @@ Sidex 对照：
 - [x] `document-resource-tab-runtime.js` 在 resource tab entry 中保留 `workspacePath`，snapshot 输出优先沿同一 workspacePath 合同。
 - [x] `local_folder_source.rs` 的真实 local_folder projection 为 mindmap/office/asset row 写入 `workspacePath.objectIdentity.assetId`，避免资源行 identity 碰撞。
 - [x] `filetree-runtime.js` 收窄 `isLocalFolder` 判定：只信 `sourceKind=local_folder`，或 sourceKind 缺失时的明确 local row/doc 前缀，避免误伤 cloud/compat id。
-- [x] 恢复 legacy `luckysheet` / `.luckysheet` table 分类，避免 table row 被误归为普通 file asset。
+- [x] 移除已退役表格引擎的 legacy 分类分支；表格资源只按当前 `table` object/icon kind 识别。
 
 本轮验证证据：