fix(tests): point the strict-mode dependency citation at README.md

Why: this branch moved the prerequisites list out of AGENTS.md into README.md
but left three references behind. The worst is run-tests.sh's --strict failure
message, which a developer is handed at the exact moment a push gate fails and
they need the dependency list: it named AGENTS.md, which no longer documents
vale, apm or jq anywhere. 56cc173 re-anchored this same class of citation in
.pre-commit-config.yaml, scripts/check-vale-style-sync.sh,
scripts/sync-marketplace-mirror.sh and tests/test-check-vale-style-sync.sh --
tests/run-tests.sh was missed, and it is the only one a human actually reads.

Implementation notes:
- run-tests.sh:262 (user-visible), run-tests.sh:16 (header rationale) and
  test-run-tests.sh:395 all now cite README.md's Prerequisites table, verified
  to name vale, apm, jq, python3/PyYAML and the claude CLI.
- Every assertion on this message greps for "a skip is a SETUP ERROR", which
  sits before the changed clause, so no test needed updating.
- test-vale-wrap.sh's bash 3.2 citation is corrected in the same pass: it
  credited LESSONS.md and the script headers, but LESSONS.md's only mention of
  3.2 is an aside inside an unrelated lesson, not a target declaration. It now
  cites scripts/lib/batch-run.sh and providers/claude-code/statusline-command.sh,
  which do declare it. The citation 56cc173 replaced was already false, so this
  finishes a half-fix rather than correcting a regression.

Impact: forced the strict-failure path with vale removed from PATH and confirmed
the corrected message printing -- 21 passed, 3 skipped, exit 1. Full suite with
vale present: 24 passed, 0 skipped, 0 failed.

Refs: #105

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TmFqzpuExLJv3m114XVE9w

tests/test-vale-wrap.sh

@@ -451,9 +451,11 @@ fi
 # cover anything new: it omitted scripts/lib/batch-run.sh — the shared runner
 # this branch introduced, whose own header (batch-run.sh:9-11) documents it as
 # bash-3.2-safe — along with four other scripts/*.sh. Deriving the list means a
-# new script is covered the moment it lands. LESSONS.md and the script headers
-# name bash 3.2 as an explicit repo target, so the scope is four globs, each
-# floor-asserted below:
+# new script is covered the moment it lands. The script headers name bash 3.2 as
+# an explicit repo target -- scripts/lib/batch-run.sh:10 ("all three callers are
+# explicitly bash-3.2-safe") and providers/claude-code/statusline-command.sh:100
+# ("macOS's system bash, and an explicit repo target") -- so the scope is four
+# globs, each floor-asserted below:
 #   - scripts/**/*.sh          — repo tooling and pre-commit hook scripts
 #   - tests/*.sh               — the runners and every regression test
 #   - plugins/*/.apm/**/*.sh   — the scripts plugins ship to users