refactor: isolate auth layout, unify tags, add editor animation and pin indicator

- Create (auth) and (app) layout groups to isolate login/setup pages
  from the main app chrome (header, sidebar, footer)
- Use window.location.href instead of goto() after login/setup to
  ensure clean full-page load across layout groups
- Add reusable TagChip component, used in TagFilter and NoteCard
- Add fade-in/pop-in entrance animation to note editor overlay
- Add persistent clickable pin indicator on pinned cards (top-right
  bookmark icon, replaces hover-only pin button for pinned notes)
- Improve "Add a crumb..." button with + icon and dashed border
- Update CLAUDE.md with retro parchment design system guidelines
- Add /.claude/ to .gitignore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -32,8 +32,8 @@ vite.config.ts.timestamp-*
 /test-results
 /playwright-report
 
-# Skills CLI (actual files are in .agents/skills/)
-/.claude/skills
+# Claude Code
+/.claude/
 
 # Local notes
 todo.md