Three keys:
- scroll: multi-line string (block scalar `|`)
- weight: fractional float (e.g. 12.5) — forces float without needing
the `!!float` tag in the target text
- title: string of digits (player needs quotes or `!!str` to avoid int)
Per-seed deterministic via ChaCha8Rng XOR'd with 0x..08.
Not wired into levels::registry() yet — integration belongs to a follow-up.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
