docs: architecture section, FAQ, cross-references, vault-memory update

README.md:
  - Added §1.5 'Architecture: Framework vs Project' with directory tree
    and lifecycle flow diagram
  - Added §2.5 FAQ covering coexistence, hooks, loops, multi-project
  - Updated install section already done in prior commit

AGENTS.md:
  - Added 'Script Cross-References' table mapping install.sh →
    onboard-project.sh → status.py --create-task

scripts/install-hooks.sh:
  - Updated header to reference onboard-project.sh as caller
  - Added 'Next step' line pointing to --create-task

vault-memory CONTEXT.md:
  - Updated test count (518→611)
  - Added new scripts (detect_models.py, onboard-project.sh)
  - Documented install/onboard flow and split architecture

AGENTS.md

@@ -136,6 +136,21 @@ Modes:
 2. Run `python3 -m pytest tests/test_prompt_paths.py` to ensure task paths are canonical.
 3. Update `CHANGELOG.md` under `[unreleased]`.
 
+## Script Cross-References
+
+The framework provides three lifecycle scripts that should be referenced from each other:
+
+| Script | Purpose | Called when | Next step |
+|---|---|---|---|
+| `scripts/install.sh` | Install framework on a fresh machine | `curl \| bash` or `git clone + bash` | → `scripts/onboard-project.sh` |
+| `scripts/onboard-project.sh` | Bootstrap automaton in a project | After framework install, per project | → `status.py --create-task` |
+| `scripts/install-hooks.sh` | Install git hooks per project | After onboarding, or manually | see `onboard-project.sh` |
+
+- `install.sh` outputs "Next: onboard-project.sh" at the end.
+- `onboard-project.sh` outputs "Next: status.py --create-task" at the end.
+- `install-hooks.sh` is called by `onboard-project.sh` automatically.
+- `update.sh` does NOT call `onboard-project.sh` — it only updates the framework.
+
 ## Adding a New Script
 
 1. Place the script in `scripts/`.