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>

src/app.css

@@ -38,6 +38,17 @@ body::before {
 	z-index: 0;
 }
 
+/* Editor entrance animations */
+@keyframes fade-in {
+	from { opacity: 0; }
+	to { opacity: 1; }
+}
+
+@keyframes pop-in {
+	from { opacity: 0; transform: scale(0.95) translateY(8px); }
+	to { opacity: 1; transform: scale(1) translateY(0); }
+}
+
 /* Prose overrides for parchment theme */
 .prose {
 	--tw-prose-body: var(--text);