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/DeepSpace.tsx

@@ -97,8 +97,8 @@ function makeStars(count: number, seedBase: number): Star[] {
 
 export function DeepSpaceOverlay({ reduced }: SeasonalOverlayProps) {
   // Two parallax depths. Far = dense + faint, Near = sparser + slightly larger.
-  const farStars = useMemo<Star[]>(() => makeStars(16, 1000), []);
-  const nearStars = useMemo<Star[]>(() => makeStars(12, 2000), []);
+  const farStars = useMemo<Star[]>(() => makeStars(40, 1000), []);
+  const nearStars = useMemo<Star[]>(() => makeStars(22, 2000), []);
 
   const heroStars = useMemo<HeroStar[]>(
     () =>
@@ -144,7 +144,7 @@ export function DeepSpaceOverlay({ reduced }: SeasonalOverlayProps) {
           position: 'absolute',
           inset: '-6%',
           contain: 'layout paint style',
-          backgroundColor: 'oklch(0.2 0.12 300 / 0.16)',
+          backgroundColor: 'oklch(0.2 0.12 300 / 0.12)',
           backgroundImage: [
             'radial-gradient(120% 90% at 50% -8%, oklch(0.28 0.13 295 / 0.2) 0%, transparent 60%)',
             'radial-gradient(100% 80% at 12% 18%, oklch(0.55 0.2 330 / 0.1) 0%, transparent 55%)',