docs: update SPEC, CONTRIBUTING, README for v0.3.0 and v0.4.0 features
- SPEC.md: add notes full-text search, contacts vCard import/export,
recurrence_parent_id + budget_recurrence_skipped table, sync_config table
- CONTRIBUTING.md: fix test file location (project root, not tests/),
add offline.html to project structure
- README.md: Node.js ≥22, Apple CalDAV UI setup (Option A), fix
Contributing section link, update Notes/Contacts feature highlights
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Ulas
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