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

rust/crates/mnote-web/browser/sidebar-filetree-open-runtime.js

@@ -304,7 +304,14 @@ export const createSidebarFileTreeOpenRuntime = (dependencies = {}) => {
       documentId: String(input && input.documentId || currentDocumentId() || '').trim(),
       workspaceId: String(input && input.workspaceId || resolveWorkspaceId(document.body) || '').trim(),
       workspacePath: workspacePath,
-      paneRole: String(input && input.paneRole || 'primary').trim() || 'primary'
+      paneRole: String(input && input.paneRole || 'primary').trim() || 'primary',
+      evidenceLocator: input && input.evidenceLocator && typeof input.evidenceLocator === 'object' ? input.evidenceLocator : null,
+      page: input && input.page,
+      bbox: input && input.bbox,
+      sourceMapPath: String(input && input.sourceMapPath || '').trim(),
+      blockId: String(input && input.blockId || '').trim(),
+      lineRange: input && input.lineRange,
+      charRange: input && input.charRange
     });
   }