fix(seasonal): keep Arcade + Deep Space overlays out of the chat text

Arcade:
- perspective grid is masked through the central timeline column so it
  frames the chat instead of striping messages; lower opacity, thinner
  non-scaling strokes (also fixes the grid vanishing in the 76px swatch)
- neon horizon line is broken through the middle so it never underlines
  a message; softer sun glow
- "1UP" score + "INSERT COIN" moved from top-left/bottom-centre (space
  bar / composer) to a single bottom-right HUD stack; font-size clamps
  to 0 via cqw inside the settings swatch so no more clipped glyphs
- scanlines: 4px pitch at lower opacity (light theme was fully striped);
  ambient wash slightly lighter

Deep Space:
- starfield 28 → 62 stars across the two parallax layers
- base violet wash slightly lighter for light themes

SeasonalPreview wrapper is now a size container (container-type) so
overlays can scale/hide fixed-px details with cqw. LOTUS_FEATURES.md
theme table now describes what both overlays actually render.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/seasonal/themes/Arcade.css.ts

@@ -102,12 +102,12 @@ export const animSparkleTwinkle = keyframes({
  * Opacity + a hair of scale for a CRT bloom feel.
  */
 export const animCoinBlink = keyframes({
-  '0%': { opacity: '0.85', transform: 'translateX(-50%) scale(1)' },
-  '6%': { opacity: '1', transform: 'translateX(-50%) scale(1.015)' },
-  '12%': { opacity: '0.85', transform: 'translateX(-50%) scale(1)' },
-  '49%': { opacity: '0.85', transform: 'translateX(-50%) scale(1)' },
-  '50%': { opacity: '0', transform: 'translateX(-50%) scale(1)' },
-  '100%': { opacity: '0', transform: 'translateX(-50%) scale(1)' },
+  '0%': { opacity: '0.85', transform: 'scale(1)' },
+  '6%': { opacity: '1', transform: 'scale(1.015)' },
+  '12%': { opacity: '0.85', transform: 'scale(1)' },
+  '49%': { opacity: '0.85', transform: 'scale(1)' },
+  '50%': { opacity: '0', transform: 'scale(1)' },
+  '100%': { opacity: '0', transform: 'scale(1)' },
 });
 
 /**