Game dev: combat animation

Distilled from the Thornvigil knight-and-archer pass (2026-09-30 to 10-01, releases 1.0.71 and 1.0.72). Its outcome:

• Arms and hands won 5 of 8 blind A/B comparisons against the previous release.
• The archer's broken anchor and the knight's frozen, straight-armed follow-through were fixed.
• Seven rounds of fixes came from traps that numbers would have caught earlier. Those traps are listed below.

Read references/thornvigil.md for the project's files, commands and current state, and references/traps.md before changing keys.

The loop