feat(notes): export note folders as portable HTML sites

[antonreshetov]

Summary

• export a notes folder as a portable static HTML site with recursive navigation, breadcrumbs, internal links, images, and drawing previews
• add a local full-text search index that works without a server and preserves the query while browsing results
• fail explicitly for unavailable cloud content and keep incomplete exports out of the destination
• align single-note HTML/PDF and folder-site rendering, and split the exporter into focused modules

Checks

• pnpm exec eslint on the affected exporter, IPC, and test files
• pnpm test for notes folder export, search runtime, note export, and drawing export coverage
• git diff --check
• main TypeScript emit verified for the facade and index modules; the full command still reports the pre-existing top-level await error in src/main/tests/mainLifecycle.test.ts:107