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

scripts/task522-page-aggregate-compat-fallback-contract.js

@@ -32,6 +32,10 @@ function firstTableCellText(doc) {
   return doc?.content?.[0]?.content?.[0]?.content?.[0]?.content?.[0]?.content?.[0]?.text || "";
 }
 
+function taskItemChecked(doc) {
+  return doc?.content?.[0]?.content?.[0]?.attrs?.checked;
+}
+
 const {
   pageBodyTiptapDocumentSource,
   pageBodyTiptapDocument,
@@ -99,6 +103,24 @@ assert.equal(
   "Provider 类别",
 );
 
+const localWithProjectedTodo = {
+  projectionSource: "local_markdown.content",
+  blockDocument: {
+    documentId: "local-md:design~2F07-ai~2Fprocess~2F7-46-document-evidence-retrieval-kernel-v1.md",
+    rootBlockIds: ["todo-1"],
+    blocks: [{
+      blockId: "todo-1",
+      type: "todo",
+      attrs: { checked: true },
+      contentNodes: [{ text: "graph traversal 结果必须带证据引用。", styles: {} }],
+    }],
+  },
+};
+assert.equal(
+  taskItemChecked(pageBodyTiptapDocument(localWithProjectedTodo)),
+  true,
+);
+
 const localLegacyOnly = {
   projectionSource: "local_markdown.content",
   content: legacyContent,