feat(notes): export notes to HTML and PDF - #890

Summary

• Add export of individual notes to HTML and PDF from the context menu.
• Preserve Markdown, frontmatter, local images, and embedded Drawings previews.
• Improve exported layout with wrapped fenced code, framed images, and YAML frontmatter formatting.
• Add success, error, and unavailable cloud-note feedback.

Tests

• pnpm test src/main/__tests__/notesExport.test.ts src/renderer/components/notes/__tests__/drawingExport.test.ts
• Scoped ESLint for the affected main and renderer files.
• pnpm i18n:copy