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/task495-filetree-copy-id-absolute-path-smoke.js

@@ -262,9 +262,9 @@ async function main() {
     selectedSidebarFileTreeSelection: { selectedRowIds: new Set(), focusedRowId: null },
   });
   assert.equal(
-    runtime.classifySidebarFileTreeAsset(new FakeCommandRow({}, "legacy.luckysheet", "luckysheet")),
+    runtime.classifySidebarFileTreeAsset(new FakeCommandRow({ "data-object-kind": "table" }, "table.asset", "table")),
     "table",
-    "legacy luckysheet 行仍应归为 table 资源",
+    "table objectKind/iconKind 行应归为 table 资源",
   );
   const dirtyCommandRow = new FakeCommandRow({
     "data-row-id": "local:markdown:docs/Page.md",