Remove deprecated setAppCacheEnabled call

The setAppCacheEnabled() method was deprecated in API 18 and removed
in newer Android versions. Removing it to fix compilation errors.

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

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

app/src/main/kotlin/uk/silverlabs/silverdroid/ui/webview/WasmWebView.kt

@@ -98,7 +98,6 @@ fun WasmWebView(
 
                         // Enable caching for offline support
                         settings.cacheMode = WebSettings.LOAD_DEFAULT
-                        settings.setAppCacheEnabled(true)
 
                         // Enable mixed content (for development)
                         settings.mixedContentMode = WebSettings.MIXED_CONTENT_ALWAYS_ALLOW