fix(react): round 25: per-agent hues, kind as lightness (0.21.11)

**Problem.** Blind round 25 (agent-record 0.90.23, charts 0.21.10) scored 32 of 252, level with round 24, and colour fell to 0 of 36. All three judges in all 12 pairs said the fixed indigo/cyan step colours read as "a cyan monoculture" where "agents blur together". The reviewer's lever (disco-evolve-run, 19:08Z): agent identity as hue, step kind as lightness within that hue, and one warm accent for the slowest and failure.

Run ID: run_369e8dcc6188e337ad6eda9097f3a5e9