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

keep-notes/app/(auth)/reset-password/page.tsx

@@ -0,0 +1,95 @@
+'use client'
+
+import { useState, Suspense } from 'react'
+import { Button } from '@/components/ui/button'
+import { Input } from '@/components/ui/input'
+import { Card, CardContent, CardDescription, CardFooter, CardHeader, CardTitle } from '@/components/ui/card'
+import { resetPassword } from '@/app/actions/auth-reset'
+import { toast } from 'sonner'
+import { useSearchParams, useRouter } from 'next/navigation'
+import Link from 'next/link'
+
+function ResetPasswordForm() {
+  const searchParams = useSearchParams()
+  const router = useRouter()
+  const [isSubmitting, setIsSubmitting] = useState(false)
+  
+  const token = searchParams.get('token')
+
+  const handleSubmit = async (e: React.FormEvent<HTMLFormElement>) => {
+    e.preventDefault()
+    if (!token) return
+
+    const formData = new FormData(e.currentTarget)
+    const password = formData.get('password') as string
+    const confirm = formData.get('confirmPassword') as string
+
+    if (password !== confirm) {
+      toast.error("Passwords don't match")
+      return
+    }
+
+    setIsSubmitting(true)
+    const result = await resetPassword(token, password)
+    setIsSubmitting(false)
+    
+    if (result.error) {
+      toast.error(result.error)
+    } else {
+      toast.success('Password reset successfully. You can now login.')
+      router.push('/login')
+    }
+  }
+
+  if (!token) {
+    return (
+      <Card className="w-full max-w-[400px]">
+        <CardHeader>
+          <CardTitle>Invalid Link</CardTitle>
+          <CardDescription>This password reset link is invalid or has expired.</CardDescription>
+        </CardHeader>
+        <CardFooter>
+          <Link href="/forgot-password" title="Try again" className="w-full">
+            <Button variant="outline" className="w-full">Request new link</Button>
+          </Link>
+        </CardFooter>
+      </Card>
+    )
+  }
+
+  return (
+    <Card className="w-full max-w-[400px]">
+      <CardHeader>
+        <CardTitle>Reset Password</CardTitle>
+        <CardDescription>Enter your new password below.</CardDescription>
+      </CardHeader>
+      <form onSubmit={handleSubmit}>
+        <CardContent className="space-y-4">
+          <div className="space-y-2">
+            <label htmlFor="password">New Password</label>
+            <Input id="password" name="password" type="password" required minLength={6} autoFocus />
+          </div>
+          <div className="space-y-2">
+            <label htmlFor="confirmPassword">Confirm New Password</label>
+            <Input id="confirmPassword" name="confirmPassword" type="password" required minLength={6} />
+          </div>
+        </CardContent>
+        <CardFooter>
+          <Button type="submit" className="w-full" disabled={isSubmitting}>
+            {isSubmitting ? 'Resetting...' : 'Reset Password'}
+          </Button>
+        </CardFooter>
+      </form>
+    </Card>
+  )
+}
+
+export default function ResetPasswordPage() {
+  return (
+    <main className="flex items-center justify-center md:h-screen p-4">
+      <Suspense fallback={<div>Loading...</div>}>
+        <ResetPasswordForm />
+      </Suspense>
+    </main>
+  )
+}