Biome's 'check' command runs both formatting and linting, causing
overlapping failures that prevented auto-format from triggering.
Split into separate commands and removed web-lint check since Biome
linting crashes on Svelte 5 syntax. Renamed check steps for clarity.
Move all [script("bun")] blocks into standalone TypeScript files under
scripts/ with shared utilities in scripts/lib/. The Justfile is now ~40
lines of thin `bun scripts/*.ts` wrappers.
Shared code consolidated into two lib files:
- lib/proc.ts: process spawning (run, spawnCollect, raceInOrder, ProcessGroup)
- lib/fmt.ts: color output, elapsed timers, reusable flag parser
