fix(engine): Android HUD QA — glyph, avatar, toggle, modal-dismiss safety

Bug A: Replace U+21C4 (tofu on FiraMono) with plain ASCII "M" on the
Modes action button.

Bug B: HudAvatar disc was invisible against BG_HUD_BAND (same dark
grey). Switch background to ACCENT_PRIMARY and text to TEXT_PRIMARY so
the disc is clearly visible.

Bug C/D: toggle_hud_on_tap improvements:
- Drain buffered TouchInput events in the early-return path (scrim
  present or paused) so the modal-dismiss frame does not replay the
  button tap's Started+Ended pair as a spurious toggle.
- Stop clearing start_pos on TouchPhase::Moved — Android fires Moved
  even for clean taps (jitter), and the distance check at Ended already
  rejects real drags via drag.is_idle(). Clearing it silently swallowed
  toggle attempts on physical devices.
- Increase HUD_TAP_SLOP_PX from 15 → 25 for better tap recognition.

Also reduces Android HUD_BAND_HEIGHT from 128 → 80 px now that action
buttons live in the bottom bar rather than the top band.

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

solitaire_engine/src/layout.rs

@@ -77,15 +77,14 @@ const MAX_TABLEAU_CARDS: f32 = 13.0;
 /// (action buttons, Score / Moves / Timer readouts). The card grid starts
 /// below this band so the HUD doesn't bleed into the play surface.
 ///
-/// Desktop: 64 px fits the single-row action bar plus the Score/Moves line.
-/// Android: 128 px accommodates the two-row button wrap on narrow phones
-/// (7 buttons × ~52 dp each, with a 65% max-width constraint, wraps to two
-/// ~48 dp rows plus row-gap). Without this larger reserve the bottom row of
-/// buttons overlaps the top card row.
+/// Desktop: 64 px fits the score/moves/time + mode badge rows.
+/// Android: 80 px gives the same content rows comfortable clearance.
+/// (Previously 128 px when action buttons lived in the top band; those are
+/// now in the bottom bar so the larger reserve is no longer needed.)
 #[cfg(not(target_os = "android"))]
 pub const HUD_BAND_HEIGHT: f32 = 64.0;
 #[cfg(target_os = "android")]
-pub const HUD_BAND_HEIGHT: f32 = 128.0;
+pub const HUD_BAND_HEIGHT: f32 = 80.0;
 
 /// Table background colour (dark green felt).
 pub const TABLE_COLOUR: [f32; 3] = [0.059, 0.322, 0.196];