fix(multi): resolve 3 remaining Android UI bugs

- radial_menu: replace active_id.unwrap() with let Some guard — no
  runtime panic possible even if DragState races (§2.3)
- card_plugin: add bottom-right AndroidCornerBg overlay to mask the
  rotated baked-in text on classic PNG cards (mirrors top-left treatment)
- hud_plugin: bump Android action button min_width 44→52 px to give
  ~22px glyphs adequate padding after dynamic font-size increase
- layout: fix doc-lazy-continuation clippy lint in BOTTOM_BAR_HEIGHT comment

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

solitaire_engine/src/layout.rs

@@ -117,6 +117,7 @@ pub const HUD_BAND_HEIGHT: f32 = 112.0;
 ///
 /// Derivation (Android): `min_height 44 px` buttons
 ///   + `padding.top 8 px` + `padding.bottom 8 px` outer bar padding = **60 px**.
+///
 /// Desktop: no persistent bottom bar, so 0.
 #[cfg(not(target_os = "android"))]
 const BOTTOM_BAR_HEIGHT: f32 = 0.0;