style: standardize layout widths and padding across all pages

Ensure consistent spacing and alignment between header, main content, and footer:
- Update Navbar to use max-w-7xl and px-8 (matching Footer)
- Standardize all page containers to use px-8 py-12 padding
- Change home page from max-w-5xl to max-w-7xl for consistency
- Update all 12 pages to use consistent padding (px-8 py-12 instead of p-8)

This creates a unified visual alignment across the entire application,
with all content sections (navbar, main, footer) using the same
max-width (7xl) and horizontal padding (px-8).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/palettes/harmony/page.tsx

@@ -52,7 +52,7 @@ export default function HarmonyPage() {
   };
 
   return (
-    <div className="min-h-screen p-8">
+    <div className="min-h-screen px-8 py-12">
       <div className="max-w-7xl mx-auto space-y-8">
         <div>
           <h1 className="text-4xl font-bold mb-2">Harmony Palette Generator</h1>