brand identity overhaul: match BRAND-IDENTITY.md across all pages

Design system changes (per brand guide):
- ZERO rounded-2xl/3xl remaining (was 131 instances)
- ZERO bg-gradient remaining (was 25) — all solid colors
- ZERO colored shadows (shadow-trust-blue, etc) — flat, no glow
- ZERO backdrop-blur/glass effects — solid backgrounds
- ZERO emoji in logo marks — square P logomark everywhere
- ZERO decorative scale animations (group-hover:scale-105, etc)

Tailwind config:
- Added brand color names: midnight, promise-blue, generosity-gold, fulfilled-green, alert-red, paper
- Kept legacy aliases (trust-blue, etc) for backwards compat
- --radius: 0.75rem → 0.5rem (tighter corners)

CSS:
- Removed glass, glass-dark, card-hover, pulse-ring, bounce-gentle, confetti-fall, scale-in animations
- Kept only purposeful animations: fadeUp, fadeIn, slideDown, shimmer, counter-roll
- --primary tuned to match Promise Blue exactly

Components:
- Button: removed all colored shadows, added 'blue' variant, removed rounded from sizes
- All UI components: rounded-xl/2xl → rounded-lg

Pages updated (41 files):
- Dashboard layout: solid header (no blur), border-l-2 active indicator, midnight logo mark
- Login/Signup: paper bg (no gradient), midnight logo mark, no emoji
- Pledge flow: solid color icons, no gradient progress bars
- All dashboard pages: flat, sharp, editorial

pledge-now-pay-later/src/components/ui/textarea.tsx

@@ -5,7 +5,7 @@ const Textarea = React.forwardRef<HTMLTextAreaElement, React.TextareaHTMLAttribu
   ({ className, ...props }, ref) => (
     <textarea
       className={cn(
-        "flex min-h-[80px] w-full rounded-xl border border-input bg-background px-4 py-3 text-sm ring-offset-background placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-trust-blue focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-50",
+        "flex min-h-[80px] w-full rounded-lg border border-input bg-background px-4 py-3 text-sm ring-offset-background placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-trust-blue focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-50",
         className
       )}
       ref={ref}