refactor(pre-commit): drop the tool-owned round-trip test for #102

The apm-audit-ci pre-push hook already fails when pretty-format-json sorts
apm-owned JSON, so a dedicated test only improved the diagnosis while adding
~100 lines of bash and a pre-commit cache dependency. Remove the test and the
comment, gates.md and LESSONS.md text that pointed at it; the --no-sort-keys
fix itself is unchanged.

Refs: #102

Co-Authored-By: Claude Code <[email protected]>
Claude-Session: https://claude.ai/code/session_01KkT7RSDwDbmrM9T34b6sTi

.pre-commit-config.yaml

@@ -35,9 +35,8 @@ repos:
         # default sorts keys, rewrites that into a form apm would never produce,
         # and the `apm-audit-ci` pre-push hook then reports drift on a file with
         # no git diff (#102, first hit at 2e395a4). Keeping insertion order means
-        # those two files need no exclude:
-        # tests/test-pretty-json-tool-owned.sh pins that they round-trip
-        # untouched.
+        # those two files need no exclude. Dropping the flag is caught at pre-push
+        # by `apm-audit-ci` as drift on `.claude/settings.json`.
         #
         # `.claude-plugin/marketplace.json` is the one remaining exclude. It
         # round-trips except for non-ASCII: it carries literal em dashes and the