Set up Vitest with jsdom environment and Tauri mocks for frontend testing.
Add 44 frontend tests covering Zustand stores (claude-chat, project, proposed-changes,
template) and lib utilities (template-registry, file type classification).
Add 48 Rust unit tests across zotero (OAuth helpers), slash_commands (markdown parsing),
latex (error extraction, SyncTeX parsing), and claude (session dir encoding, message
title cleaning). Update README with test commands.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
