refact(comments): state the mechanism, not the incident

Every comment that invoked a 'law' (50 word-boundary sites across 28
tracked files) now states what is going on and why, in terms that
transfer to any project: gate twins drift until one side greenlights
what the other refuses; a tag re-points while a digest pins; a
restrictive engine behavior belongs to the runtime that imposed it and
must be re-tested, not inherited; a speculative head is tensors in the
file, not a flag; snapshot links dangle where the container resolves
them; exit 0 is a clean stop to systemd, so a self-exiting daemon on
on-failure goes dark reporting success. Event narratives and dates are
gone from these comments; the mechanics carry the argument.

Behavior-identical: bash -n, py_compile, yaml parse, full bats suite
408/408 green. One symbol rename rides along (stack script local
scale_law -> scale_contract, with its log text).

tests/llm_units.bats

@@ -85,9 +85,9 @@ unit_repo_path() {
     # Restart=always, not on-failure. Every endpoint here is a container
     # runner (podman run) or a server whose front end can exit 0 on a
     # control-plane event; systemd treats exit 0 as a CLEAN stop and
-    # on-failure leaves the endpoint dark until the next boot, with the unit
-    # reporting success. frank-archon learned this on 2026-10-04; the fleet
-    # law is that no LLM unit may ship the weaker policy.
+    # on-failure leaves the endpoint dark until the next boot, with the
+    # unit reporting success. No LLM unit may ship the weaker policy: a
+    # single endpoint on on-failure is a daemon that goes dark silently.
     local unit
     while IFS= read -r unit; do
         grep -qx 'Restart=always' "$unit" || {