fix(android): P3 keyboard-hint sweep + clipboard JNI verified

Suppress all remaining keyboard-accelerator chips/labels on Android:
- spawn_modal_button (ui_modal.rs): single cfg gate covers every modal
  across all 13+ callers (onboarding, pause, confirm, game-over, restore,
  play-by-seed, home, help, profile, stats, leaderboard, settings, achievement)
- home_plugin.rs: mode-card hotkey chips (N/C/Z/X/T) gated off
- replay_overlay.rs: [SPACE]/[ESC]/[←→] footer hint text gated off;
  mode-indicator text kept
- help_plugin.rs: kbd chip containers gated off; description text kept

Clipboard JNI verified on Pixel 7 AVD (Android 14): added temporary
KEYCODE_C test hook, logcat confirmed "clipboard JNI OK", hook reverted.
Both JNI bridges (keystore + clipboard) are now confirmed working on device.

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

solitaire_engine/src/replay_overlay.rs

@@ -944,6 +944,7 @@ fn spawn_overlay(
                         },
                         TextColor(TEXT_SECONDARY),
                     ));
+                    #[cfg(not(target_os = "android"))]
                     footer.spawn((
                         Text::new(keybind_footer_hint_text()),
                         TextFont {