Split the 808-line SeasonalEffect monolith into one self-contained module per
theme under seasonal/themes/ (<Theme>.tsx + <Theme>.css.ts), and gave every
theme a premium, research-backed redesign (one Opus agent per theme against a
shared brief). SeasonalEffect now just imports the 11 overlays and dispatches;
the orphaned shared Seasonal.css.ts is removed (each theme owns its keyframes).
Each overlay: layered oklch palettes, GPU-only animation (transform/opacity),
`contain: layout paint style` to kill repaint flicker, ≤~40-element perf budget,
particles seeded once via useMemo (no per-frame state), a gorgeous STATIC
prefers-reduced-motion form (the settings preview thumbnail), WCAG-AA-preserving
low opacities, and no new deps / no external assets (inline SVG data-URIs,
Tauri/CSP-safe).
Themes: Halloween, Christmas, New Year, Autumn, April Fools, Lunar New Year,
Valentines, St. Patrick's, Earth Day, Deep Space, Arcade.
Gates: tsc clean, ESLint clean, Prettier clean, build OK, 551 tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
