fix(android): remove unused JValue import and fix match arm types

Two cfg(android) issues hidden from Linux CI:
- android_clipboard.rs: JValue was imported but never used (JValueOwned
  covers all call sites). Removed to satisfy -D unused-imports.
- stats_plugin.rs: both arms of the clipboard match now return () via
  explicit block+semicolon, resolving the type mismatch that pinged-pong
  between runs due to bidirectional match-arm type inference.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/stats_plugin.rs

@@ -362,10 +362,10 @@ fn handle_copy_share_link_button(
     #[cfg(target_os = "android")]
     {
         match crate::android_clipboard::set_text(&url) {
-            Ok(()) => toast.write(InfoToastEvent(format!("Copied: {url}"))),
+            Ok(()) => { toast.write(InfoToastEvent(format!("Copied: {url}"))); }
             Err(e) => {
                 warn!("android clipboard failed: {e}");
-                toast.write(InfoToastEvent(format!("Share link: {url}")))
+                toast.write(InfoToastEvent(format!("Share link: {url}")));
             }
         }
     }