feat(gitflow): universal gitflow model — lib + skill + orchestrator wiring

lib core (start/finish/init, transactional bootstrap) + migrate + 57-test suite + aiguillage; skills/gitflow + gitignore template; CLAUDE.md gitflow rule; wiring init-project (5f/8/11), onboard (2.6), ship-feature (0/4/9), feat/bugfix/hotfix aiguillage.

lib/gitflow-aiguillage.md

@@ -0,0 +1,26 @@
+# Gitflow aiguillage — assistance flows branch on a protected base
+
+Assistance flows (`/feat`, `/bugfix`, `/hotfix`) commit IN PLACE on a working
+branch — the frequent case, behavior unchanged. But they must NEVER commit code
+on a protected base (`main`/`develop`). Run this check **before editing any
+file**. The caller passes its TYPE: feat→`feature`, bugfix→`bugfix`,
+hotfix→`hotfix`.
+
+```bash
+bash "$HOME/.claude/lib/gitflow.sh" protected-base && echo PROTECTED || echo WORKING
+```
+
+- **WORKING** (`feature/*`, `bugfix/*`, `hotfix/*`, or any non-protected branch)
+  → proceed; you commit in place on this branch. Nothing changes.
+- **PROTECTED** (`main`/`develop`) → branch first, do NOT commit here:
+  ```bash
+  bash "$HOME/.claude/lib/gitflow.sh" start <YOUR-TYPE> <short-kebab-name>
+  ```
+  `<short-kebab-name>` derived from the request. Then do the work on the new branch.
+
+**Never run `gitflow finish`** — assistance flows commit, they do not merge.
+Integration is a separate, human-gated step (the `gitflow` skill).
+
+Note: `hotfix` branches off **main** (prod) even when invoked from `develop` —
+that is the gitflow definition of a hotfix. For a dev-scoped small fix, use
+`/bugfix` (branches off develop).