fix(commit-change): add gitflow aiguillage before commit

commit-changer committed code autonomously with no branch precondition
(gitflow-conformity §2a, verified MEDIUM CONFIRMED) — on develop/main it
attempted a direct code commit, backstopped only by the pre-commit hook.
Adds Phase 0: the same `gitflow-aiguillage.md` mechanism hotfixer/bugfixer/
feater already use (TYPE=chore) — branches to chore/* on a protected base,
no-op on a working branch — plus a report-only fallback (no develop / no
lib -> ask human, don't auto-branch). Commit-plan gate + scoped staging
untouched. SKILL.md pre-flight notes the aiguillage.

Dry-run (throwaway repos, REAL lib + REAL pre-commit hook) — both paths:
  CASE 1 on develop: aiguillage -> chore/commit-pending, code commit
    SUCCEEDS, hook never blocks; contrast: same commit direct on develop
    is BLOCKED -> aiguillage is what avoids it. PASS
  CASE 2 no develop: fallback -> no auto-branch, changes uncommitted,
    no chore/* created, ask human. PASS

skills/commit-change/SKILL.md

@@ -23,5 +23,8 @@ If unreachable, emit `Commit-changer agent missing.` and STOP. Never auto-commit
 Pre-flight checks (the agent should also perform, but flag here):
 - Detached HEAD or unmerged conflicts → STOP, report state.
 - Identity unconfigured (`git config user.email` empty) → STOP, ask user.
+- On a protected base (`main`/`develop`) the agent runs the gitflow
+  aiguillage (Phase 0) and branches to `chore/*` before committing — code
+  never lands directly on a protected branch.
 
 $ARGUMENTS