refactor: streamline toast system and harmonize UI across tools

- Migrate all toast notifications to sonner and remove custom ToastProvider
- Align Card and TextInput styling across Figlet and Pastel (rounded-lg, border-based)
- Fix build error by removing non-existent export in lib/units/index.ts
- Clean up unused Figlet components and constants

app/(app)/figlet/page.tsx

@@ -2,12 +2,16 @@ import { FigletConverter } from '@/components/figlet/FigletConverter';
 
 export default function FigletPage() {
   return (
-    <div className="p-4 sm:p-8 max-w-7xl mx-auto">
-      <div className="mb-8">
-        <h1 className="text-3xl font-bold mb-2">Figlet UI</h1>
-        <p className="text-muted-foreground italic">ASCII Art Text Generator with 373 Fonts</p>
+    <div className="min-h-screen py-12">
+      <div className="max-w-7xl mx-auto px-8 space-y-8">
+        <div>
+          <h1 className="text-4xl font-bold mb-2">Figlet ASCII</h1>
+          <p className="text-muted-foreground">
+            ASCII Art Text Generator with 373 Fonts
+          </p>
+        </div>
+        <FigletConverter />
       </div>
-      <FigletConverter />
     </div>
   );
 }

app/(app)/pastel/batch/page.tsx

@@ -106,7 +106,7 @@ export default function BatchPage() {
                 value={inputColors}
                 onChange={(e) => setInputColors(e.target.value)}
                 placeholder="#ff0099, #00ff99, #9900ff
#ff5533
#3355ff"
-                className="w-full h-48 p-3 border rounded-lg bg-background font-mono text-sm"
+                className="w-full h-48 p-3 border border-border rounded-xl bg-input font-mono text-sm focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary/50 focus-visible:border-primary/50 transition-all duration-200"
               />
 
               <p className="text-xs text-muted-foreground mt-2">

app/(app)/pastel/layout.tsx

@@ -4,8 +4,8 @@ export default function PastelLayout({
   children: React.ReactNode;
 }>) {
   return (
-    <div className="p-4 sm:p-8 max-w-7xl mx-auto">
+    <>
       {children}
-    </div>
+    </>
   );
 }

app/(app)/units/page.tsx

@@ -2,12 +2,16 @@ import MainConverter from '@/components/units/converter/MainConverter';
 
 export default function UnitsPage() {
   return (
-    <div className="p-4 sm:p-8 max-w-7xl mx-auto">
-      <div className="mb-8">
-        <h1 className="text-3xl font-bold mb-2">Units Converter</h1>
-        <p className="text-muted-foreground italic">Smart unit converter with 187 units across 23 categories</p>
+    <div className="min-h-screen py-12">
+      <div className="max-w-7xl mx-auto px-8 space-y-8">
+        <div>
+          <h1 className="text-4xl font-bold mb-2">Units Converter</h1>
+          <p className="text-muted-foreground">
+            Smart unit converter with 187 units across 23 categories
+          </p>
+        </div>
+        <MainConverter />
       </div>
-      <MainConverter />
     </div>
   );
 }

app/globals.css

@@ -110,6 +110,7 @@
 }
 
 :root, .dark {
+  color-scheme: dark;
   /* CORPORATE DARK THEME (The Standard) */
   --background: #0a0a0f;
   --foreground: #ffffff;
@@ -134,6 +135,7 @@
 }
 
 .light {
+  color-scheme: light;
   /* LIGHT ADAPTATION (Keeping the "Glass" look) */
   --background: oklch(98% 0.005 255);
   --foreground: oklch(20% 0.04 255);
@@ -166,6 +168,10 @@
     -webkit-font-smoothing: antialiased;
     -moz-osx-font-smoothing: grayscale;
   }
+  /* Fix native select dropdown styling */
+  select option {
+    @apply bg-popover text-popover-foreground;
+  }
 }
 
 html {