chore(tidy): T-2 — remove out-of-scope submarine-game docs from root (#360)

## Summary

Phase T-2 of the repo-tidy stack (per the owner's "Delete outright"
instruction in the tidy plan).

Removes three large root-level documents that describe a *submarine
game* (`DAMAGE-SYSTEM.md` 1,071 lines, `CONTROLS-REFERENCE.md` 556
lines, `GAME-BUNDLING-STRATEGY.md` 552 lines — 2,182 lines combined).
They sit at the root of the AffineScript *compiler* repository and have
zero incoming references — `grep -r` across the working tree's
`.md`/`.adoc`/`.yml`/code surface finds no hits.

They appear to be artefacts of an earlier experimental game project that
bled into this repo via an old merge or templating mishap. The current
language / typed-wasm / stdlib work has no use for any of it; if a
future AffineScript-built game needs a damage model / control scheme /
bundling strategy, the right place for those docs is the game's own
repo, not the compiler's.

Git history preserves the deleted content.

## Test plan

- [ ] CI green (no callers exist; expected to be a pure-delete no-op).
- [ ] Repo-root listing visibly shorter; this clears 3 of the 12 loose
root `.md` files the broader tidy is addressing.

## Stack

- ✅ T-1 (#359) — AI manifest rename + TECH-DEBT canonical name
- 🟡 **T-2 (this PR)** — game-file deletion
- T-3 — move loose root docs into `docs/` subtree
- T-4 — `RSR_COMPLIANCE.adoc` + `STATE.scm` per RSR template
- T-5 — refresh `wiki/`
- T-6 — issue / PR triage

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_Generated by [Claude
Code](https://claude.ai/code/session_01WNkH8UucP3PppG5R36kGcu)_

Co-authored-by: Claude <noreply@anthropic.com>

Author: hyperpolymath