feat(check): every skill states when it stops and hands back

Implements #5's decision. The hard part was #37's, not #5's: which skills need
an escalation rule? A hardcoded list rots, sniffing the prose for "does this
write anything" is unfalsifiable, and a frontmatter flag is the option #5
rejected wearing a hat.

So there is no acting set. Every skill answers the question, and a read-only one
answers it in a line. That turns an absence into a claim someone can disagree
with, which is the whole point — "this skill never hands back" is a design
decision worth stating, and today it was indistinguishable from nobody having
thought about it.

Eleven written here, all advisory or read-only, where the honest answer is short
and the value is in being specific rather than generic. `cognitive-load` stops
when the metric disagrees with the people reading the code, because that is
evidence about the metric. `test-design` stops when the tests are fine and the
design under test is what makes them awkward. `code-review` stops when the diff
is big enough that a review would be a skim, and says so rather than producing
confident coverage of a fraction.

The remaining thirty are the acting set — writes, dispatches, credentials,
releases — and each needs a rule someone thought about rather than a rote
paragraph, so they sit in bin/escalation-pending.txt. That list only shrinks,
and it is self-cleaning: a listed skill that HAS a section fails the gate, so an
exemption cannot outlive its reason. Mutation-verified both ways.

Six test cases including the stale-entry case, because an exemption for a skill
that no longer exists is how a gate quietly stops covering something.

Refs #37, closes the mechanism half
Bump-Type: minor

Taskfile.yml

@@ -114,7 +114,12 @@ tasks:
         #    session_id is its only required field, and nine skills omitted it.
         sh '{{.TASKFILE_DIR}}/bin/check-session-log' '{{.TASKFILE_DIR}}' || fail=1
 
-        # 6. Plugin manifest version must match the latest tag, or installers
+        # 6. Every skill says when it stops and hands back (#5). Skills whose
+        #    rule is not written yet are listed in bin/escalation-pending.txt,
+        #    which only shrinks.
+        sh '{{.TASKFILE_DIR}}/bin/check-escalation' '{{.TASKFILE_DIR}}' || fail=1
+
+        # 7. Plugin manifest version must match the latest tag, or installers
         #    never see the update (Claude Code gates updates on this field).
         if [ -f '{{.PLUGIN_MANIFEST}}' ]; then
           manifest_v=$(sed -n 's/.*"version"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' '{{.PLUGIN_MANIFEST}}' | head -1)