fix(coordination): restore missing .gitmodules for absolute-zero submodule

The absolute-zero/ gitlink (160000 commit ad085ba) was recorded in the
index but .gitmodules was never committed, leaving a dangling submodule
pointer: `git submodule` could not resolve it and the Mustfile
`submodule-recorded` check (severity: critical) always failed.

Eight machine-readable contractiles (Mustfile, Bustfile, Dustfile,
Intentfile, Trustfile, gitbot-fleet, hypatia) document absolute-zero/ as
a pinned submodule (PR #89); only the README contradicted them by calling
it "referenced, not vendored as a submodule". Restore .gitmodules pinned
to hyperpolymath/absolute-zero and reconcile the README to match the
documented intent.

Verified: `git config -f .gitmodules submodule.absolute-zero.url` now
succeeds and `git submodule status` resolves the pointer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015qwVESTcbfanY2iJPQNoSz

Author: claude

.gitmodules

@@ -0,0 +1,8 @@
+# The Certified Null Operation (CNO) reference is developed in the standalone
+# hyperpolymath/absolute-zero repository and pinned here as a submodule (PR #89).
+# CNO development happens upstream; this pointer is bumped as a deliberate act
+# (see .machine_readable/contractiles/Intentfile.a2ml and Trustfile.a2ml).
+[submodule "absolute-zero"]
+	path = absolute-zero
+	url = https://github.com/hyperpolymath/absolute-zero.git
+	branch = main

README.md

@@ -21,9 +21,11 @@ secure, and sustainable systems.
 > This repository serves as the official hub and governance center for
 > the MAA Framework project. Implementation work lives in-tree under
 > `aletheia/` (the microkernel, Rust); the Certified Null Operation is
-> the standalone `hyperpolymath/absolute-zero` repository, coordinated
-> here (referenced, not vendored as a submodule). A CRG Tier-C test
-> suite (unit, E2E, property, aspect, benchmarks) landed 2026-04-04.
+> developed in the standalone `hyperpolymath/absolute-zero` repository and
+> pinned here as a git submodule under `absolute-zero/` (PR #89) — CNO
+> development happens upstream, and this pointer is bumped deliberately. A
+> CRG Tier-C test suite (unit, E2E, property, aspect, benchmarks) landed
+> 2026-04-04.
 > Detailed specification documents will be uploaded as development
 > progresses.