docs(agents): put AGENTS.md itself in the axes' scope

This file carries the conventions rules.md, decisions.md and
mechanisms.md rest on, and it has the same failure modes -- demonstrated
in the previous commit, where axis 1 falsified two counts in the axes
note itself. So the trigger now names four files, not three.

Not wholesale, though. Axes 3, 5 and 6 need rule statements, examples
and interacts:, which only rules.md has; asking a reviewer to run
rule-vs-its-own-examples against AGENTS.md is asking for something
meaningless, and a checklist that does that teaches the reader to
skim it. The note says which six apply and asks the reviewer to
report what they skipped as inapplicable.

Checking that also ran axis 7 (general clause vs actual scope) over
the skip-list, which named five machine-checked things where there
are nine tests -- a reviewer could have burned effort reporting a
broken interacts: ID or an unresolved cross-doc anchor, both already
enforced. The list is now complete and points at the two test files
as the authority, saying in as many words that it goes stale as
guards are added.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: derek73

AGENTS.md

@@ -135,16 +135,29 @@ from the weakest instrument manufactures confidence rather than
 supplying it.
 
 **Reviewing a docs/design change: the nine axes.** Run these before
-merging anything that touches rules.md, decisions.md or mechanisms.md.
+merging anything that touches rules.md, decisions.md, mechanisms.md —
+or THIS FILE, which carries the conventions those three rest on and
+has the same failure modes. Axes 3, 5 and 6 are rules.md-specific
+(they need rule statements, examples and `interacts:`); the other six
+apply to any of the four. Say which axes you ran and which you skipped
+as inapplicable — a checklist that asks for something meaningless
+teaches the reader to skim it.
 Each was earned by a defect that survived every other check on #386,
 where the review passes surfaced ten issues in total — nine of them
 by these axes, one by the spec self-review above — and unaided prose
 reading surfaced none. The parenthetical is the case that earned the
-axis. Skip
-what the suite already enforces — example lines, `deviates:` today-
-values, boundaries, the one-of `implemented:`/`tracked:` rule, and
-citation excerpts are all machine-checked, so a finding those would
-have caught is a false positive.
+axis.
+
+Skip what the suite already enforces. `tests/v2/test_rules_doc.py`
+and `tests/v2/test_doc_citations.py` machine-check example lines and
+their `deviates:` today-values, boundaries, the one-of
+`implemented:`/`tracked:` rule, `implemented:` against the modules
+that actually cite the rule, `interacts:` and cross-doc anchor IDs,
+citation excerpts quoted verbatim, and legacy citation forms. Assume
+they pass; a finding one of them would catch is a false positive.
+Read those two files rather than trusting this sentence — it named
+five of the nine guards when written, and goes stale as guards are
+added.
 
 1. **Recompute every number.** Any count, ratio or "N names" in the
    diff gets recomputed by a script written now, never read. (A