T07: separate a correction from a retarget with a mechanical test

A blanket "no retargeting in the measuring commit" rule would have been
wrong. CB-WP-0002 moved AC-1 three times in exactly that shape and every
move was correct -- each time a new instrument disproved the old figure.
Four legitimate corrections would have been forbidden to catch one bad
retarget.

The test is mechanical rather than a statement of intent:

  correction  the target moves and the implementation does not; legal in
              the same commit provided the instrument's output is there
  retarget    the same commit changes both the target and the code the
              target measures; requires an ADR stating why the new target
              binds on future work

Applied retroactively: AM-4a/AM-4b are UNRATIFIED. They were set after
seeing the measurement, in the commit that produced it, with the
implementation changing too -- a retarget by this test. make dep-weight
is currently enforcing a target no reviewed decision stands behind.
Recorded as an open item; ratifying or changing them is a maintainer
decision, not an implementer's.

Also: specs/InnerLoop.md split into InnerLoop.md (process) and
InnerLoopReference.md (rubric, template, rules, definition of done).
Not a stylistic choice -- `make loop-lint` failed on the commit that
pushed the file to 407 lines against its own ~400 limit. The gate added
this morning to make that rule executable caught its own author within
the hour, which is the cheapest possible demonstration that it works.

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

workplans/CB-WP-0003-loop-hardening.md

@@ -253,7 +253,7 @@ to reject.
 
 ```task
 id: CB-WP-0003-T07
-status: todo
+status: done
 priority: medium
 state_hub_task_id: "2f702821-7e64-4981-9885-82fa07f638aa"
 ```