boot: spring animation swaps flowers for flying birds + waits for full motd
Why: spring boot was all bloom; moving to a bird theme that drifts across
the screen feels more alive, and the jump out of the boot screen was
cutting off the motd mid-reveal.
- index.mjs: SPRING_BIRDS / drawTurtleBird (egg body, flapping wing,
forked tail, beak, eye+sparkle, tucked feet), horizontal drift with
edge wrap, per-bird hue/belly/beak
- index.mjs: motdComplete getter on acBootCanvas (true when all chars
have revealed at the slowest mode rate, 12 chars/s)
- boot.mjs: hideBootLog polls motdComplete every 100ms, capped at 8s
so boot can't stall
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>