Brings every descriptive doc in line with the software's actual state after
Waves 6-7 (and the Kit work that has carried the harness to v22). Driven by a
6-agent parallel audit; plan.md and CHANGELOG (append-only history) untouched.

- CLAUDE.md: 260+ -> 312 Kit handlers; harness ~125/v12 -> ~180 across 37
  tests / v22; "(from CONTRIBUTING.md)" dropped (no such file); the examples
  paragraph (spike -> spike-gamekit; platformer = 5 levels + bestiary I/II;
  slingshot 3 levels; micro-game retired in Wave 5).
- README.md / dist/INSTALL.md: "four levels" -> five; platformer bullet
  expanded (5 levels, the bestiary, joints, audio); the dead CONTRIBUTING.md
  link repointed at real targets. (Slingshot's correct "3 levels" left alone.)
- docs/building.md: the "distribution zip" section described the OLD loose-lib
  layout; rewritten for the bundled-in-extension layout make-release.py ships.
- docs/expansion-prep.md: the wave-status table + roadmap (Waves 1-7 COMPLETE,
  Wave 8 the only remaining item; baseline harness v22; the three-level
  platformer noted as a historical milestone, now five). Dated design sections
  left as history.
- docs/game-engine-spec.md: ~93 -> v22/~180 checks; b2kPlayerAnims gains
  pWall/pDash; b2kPlayerState gains wallslide/dash; the Wave 5 moves moved
  from "still ahead" to "landed".
- docs/kit-guide.md: b2Version 3 -> 4; the micro-game section reframed as a
  retired example whose pattern is preserved; added b2kSheetPersist.
- docs/kit-reference.md: added the airDash player knob (the one omitted).
- platformer header: "FOUR-LEVEL" -> FIVE; added the LEVEL 5 (SCORCHED DUNES)
  entry; wove the bestiary II creatures into the L1/L2/L4 blurbs + the feature
  summary; "the last flag" moved to L5.

api-reference.md, architecture.md, getting-started.md, prebuilt/README.md were
audited and found already accurate (no change). Static gates pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0181ux7LaTgpy4cosAcL4dia