fix(website): use local library build and fix CSP issues

Critical fixes to resolve library loading failures:

**Issue**: CornerKit library was not loading from CDN (404 errors)
**Root Cause**: Library not yet published to npm, so jsdelivr/unpkg CDN URLs fail

**Changes**:
1. Copy local build from packages/core/dist/cornerkit.js to website/
2. Update index.html to load from local build instead of CDN
3. Fix CSP to allow placeholder images (via.placeholder.com)
4. Remove frame-ancestors from meta CSP (should be HTTP header only)

**Result**: Library now loads successfully, smoothing parameter works correctly

Tested with local server - all functionality working:
- Hero animations
- Playground sliders (radius & smoothing)
- Gallery examples (26 components)
- Comparison section
- Keyboard shortcuts (R, I)
- Code generation and clipboard copy

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

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

Author: bejarcode

website/cornerkit.js

@@ -18,7 +18,7 @@
   <meta property="og:image" content="https://bejarcode.github.io/cornerkit/assets/og-image.png">
 
   <!-- Security -->
-  <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline' https://cdn.jsdelivr.net; style-src 'self' 'unsafe-inline'; img-src 'self' data:; font-src 'self'; connect-src 'self'; base-uri 'self'; form-action 'self'; frame-ancestors 'none';">
+  <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https://via.placeholder.com; font-src 'self'; connect-src 'self'; base-uri 'self'; form-action 'self';">
 
   <!-- Favicon -->
   <link rel="icon" type="image/svg+xml" href="assets/favicon.svg">
@@ -513,9 +513,8 @@ <h4>Vue (Coming Soon)</h4>
     </div>
   </footer>
 
-  <!-- CornerKit from CDN with fallback -->
-  <script src="https://cdn.jsdelivr.net/npm/@cornerkit/core@1.0.0/dist/cornerkit.js"
-          onerror="this.onerror=null; this.src='https://unpkg.com/@cornerkit/core@1.0.0/dist/cornerkit.js'"></script>
+  <!-- CornerKit library (local build until published to npm) -->
+  <script src="cornerkit.js"></script>
   <script src="app.js"></script>
 </body>
 </html>