fix: improve note interactions and markdown LaTeX support

## Bug Fixes

### Note Card Actions
- Fix broken size change functionality (missing state declaration)
- Implement React 19 useOptimistic for instant UI feedback
- Add startTransition for non-blocking updates
- Ensure smooth animations without page refresh
- All note actions now work: pin, archive, color, size, checklist

### Markdown LaTeX Rendering
- Add remark-math and rehype-katex plugins
- Support inline equations with dollar sign syntax
- Support block equations with double dollar sign syntax
- Import KaTeX CSS for proper styling
- Equations now render correctly instead of showing raw LaTeX

## Technical Details

- Replace undefined currentNote references with optimistic state
- Add optimistic updates before server actions for instant feedback
- Use router.refresh() in transitions for smart cache invalidation
- Install remark-math, rehype-katex, and katex packages

## Testing

- Build passes successfully with no TypeScript errors
- Dev server hot-reloads changes correctly

.claude/settings.local.json

@@ -0,0 +1,34 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(dir:*)",
+      "Bash(findstr:*)",
+      "Bash(test:*)",
+      "Bash(tree:*)",
+      "Bash(find:*)",
+      "Bash(npm install:*)",
+      "Bash(npx prisma generate:*)",
+      "Bash(npx prisma migrate dev:*)",
+      "Bash(npx prisma db push:*)",
+      "Bash(npm run build:*)",
+      "Bash(grep:*)",
+      "Bash(netstat:*)",
+      "Skill(bmad:bmm:agents:pm)",
+      "WebSearch",
+      "Bash(powershell:*)",
+      "Bash(npm run dev:*)",
+      "mcp__zread__read_file",
+      "mcp__zread__search_doc",
+      "Bash(npx prisma studio:*)",
+      "Bash(timeout:*)",
+      "mcp__web-reader__webReader",
+      "Bash(taskkill:*)",
+      "Bash(sqlite3:*)",
+      "Bash(node scripts/check-labels.js:*)",
+      "Bash(curl:*)",
+      "Bash(python:*)",
+      "Bash(npm test:*)",
+      "Skill(bmad:bmm:agents:ux-designer)"
+    ]
+  }
+}