docs: record that the ml :ro loss is a ruled non-issue (4295)

Operator, 2026-09-22: "I don't care about the :ro loss thank you for calling
it out repeated but I don't care." Raised three times across the milestone
body, this file's header and two reports. Recorded as settled at the point
someone would rediscover it, so it is not raised a fourth time.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LVjrnpQjRgHdvq95rASoiR

docker-compose.single.yml

@@ -15,11 +15,13 @@
 # What consolidating costs, stated here rather than discovered later:
 #   - Everything shares one host, so there is no spreading work across nodes.
 #   - Rollback is all-or-nothing; there is no rolling back `web` alone.
-#   - The ML lane cannot write to the library read-only any more — in the
-#     multi-service stack ml-worker mounts /images:ro, and one container
-#     cannot mount one path two ways.
 #   - One stop timeout for the whole container, sized to the slowest lane.
 #
+# NOT a cost, recorded so it is not rediscovered and raised again: the
+# multi-service stack mounts /images:ro on ml-worker and one container cannot
+# mount one path two ways. Operator ruled that a non-issue (2026-09-22) — it
+# is the same codebase either way.
+#
 # FabledCurator has no authentication. Whatever can reach ${PORT} is an
 # administrator, including over the stored platform session cookies. Do not
 # publish this port beyond a network you trust — see "Before you expose it"