chore(tidy): T-1 — adopt 0-AI-MANIFEST.a2ml + restore docs/TECH-DEBT.adoc (#359)

## Summary

Phase T-1 of the repo-tidy stack the owner requested ("tidy of the repo
and cleanup of any mess so it is all tidy and readable"). Three
pure-rename / delete operations:

1. **`AI.a2ml` → `0-AI-MANIFEST.a2ml`** — clears the standing Hypatia
HIGH finding `root_hygiene "Stray AI.a2ml in root -- use
0-AI-MANIFEST.a2ml only"` and matches the sibling-repo convention
(`road-skate/`, `affinescript-vite/`, `affinescriptiser/` already carry
`0-AI-MANIFEST.a2ml`). Content preserved verbatim; a canonical-structure
refresh (the sibling template's STOP-banner format declaring
canonical-location invariants) is deferred to a later tidy phase to keep
this PR reviewable.
2. **`AI.djot` deleted** — clears the Hypatia HIGH finding `root_hygiene
"Superseded by 0-AI-MANIFEST.a2ml"`. The same project metadata is
already covered by `0-AI-MANIFEST.a2ml` + the six
`.machine_readable/6a2/*.a2ml` files it points at.
3. **`docs/TECH-DEBT-alt.adoc` → `docs/TECH-DEBT.adoc`** — restores the
canonical filename every cross-link in the repo already points at
(`META.a2ml`, `STATE.a2ml`, `CAPABILITY-MATRIX.adoc`, `ECOSYSTEM.adoc`,
`RESCRIPT-ELIMINATION.adoc`, `STDLIB-EXTERN-AUDIT.adoc/.a2ml`,
`docs/specs/TYPED-WASM-ROADMAP.adoc`). PR #356 had appended `-alt`
during the #351 split to avoid a merge conflict; with #351 resolved via
#355/#356 the alt suffix is dead weight and every existing cross-link
was silently broken.

Incidental: one stale path in `CONTRIBUTING.md`'s repo-layout block
updated `AI.a2ml` → `0-AI-MANIFEST.a2ml`.

## Hypatia delta (expected)

Before this PR the standing scan reports two HIGH `root_hygiene`
findings against this exact pair of files. They should drop on the next
scan, taking the totals from the 143-finding baseline down to ~141. The
TypeScript-exemption findings under `affinescript-deno-test/` are out of
scope for this PR — they're documented carve-outs in `.claude/CLAUDE.md`
§"TypeScript Exemptions (Approved)" and the policy check has no
allowlist for them.

## Test plan

- [ ] CI `governance / Language / package anti-pattern policy` and
`vscode-smoke` remain at their pre-existing baseline-failure state
(these are the documented known-failing checks in `.claude/CLAUDE.md`
§"Known-failing baseline checks"; not introduced or worsened by this
PR).
- [ ] `build`, `lint`, `migration-assistant`, `governance / Workflow
security linter`, `governance / Security policy checks`, `governance /
Well-Known (RFC 9116 + RSR)`, `governance / Code quality + docs`,
`governance / Guix primary / Nix fallback policy`, `Semgrep OSS`,
`CodeQL`, `Hypatia`, `analyze (actions, none)`,
`enforce-lowercase-stdlib`, `spark-theatre-gate` all green.
- [ ] The next Hypatia scan comment drops the two `AI.a2ml` / `AI.djot`
HIGH lines.

## Stack

This is part of a stack the owner authorised — see issue thread for the
wider scope. Subsequent phases land on separate branches off `main`:

- **T-2** — delete out-of-scope game files (`DAMAGE-SYSTEM.md`,
`CONTROLS-REFERENCE.md`, `GAME-BUNDLING-STRATEGY.md`).
- **T-3** — move loose root docs (`ABI-FFI-README.md`,
`ALPHA-1-RELEASE-NOTES.md`, `BACKEND-*`, `COMPILER-CAPABILITIES.md`,
`KNOWN-ISSUES.md`, `LICENSING-GUIDE.md`, `NAVIGATION.adoc`,
`PROOF-NEEDS.md`, `ROADMAP.adoc`, `SECURITY-SETUP.md`, `EXPLAINME.adoc`,
`RSR_OUTLINE.adoc`) into the existing `docs/` subtree.
- **T-4** — add `RSR_COMPLIANCE.adoc` + `STATE.scm` per RSR template.
- **T-5** — refresh `wiki/`.
- **T-6** — issue/PR triage pass.

Phase 2c (#357) is on a separate branch and unaffected by this PR.

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

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

Author: hyperpolymath

AI.a2ml 0-AI-MANIFEST.a2mlAI.a2ml renamed to 0-AI-MANIFEST.a2ml

@@ -43,7 +43,7 @@ affinescript/
 ├── packages/            # Aggregate JS/TS/ReScript binding packages
 ├── editors/             # Editor integrations
 ├── js/                  # `js_of_ocaml` playground (built into `playground.bc.js`)
-├── .machine_readable/   # Machine-readable metadata (`.a2ml`) — see AI.a2ml
+├── .machine_readable/   # Machine-readable metadata (`.a2ml`) — see 0-AI-MANIFEST.a2ml
 ├── .github/             # CI workflows, issue templates
 ├── CODE_OF_CONDUCT.md
 ├── CONTRIBUTING.md      # This file