feat: auto-detect and install missing shell frameworks after restore

After mackup restores dotfiles, ~/.zshrc may reference tools (Oh My Zsh,
nvm, pyenv, rustup, …) that haven't been installed yet, causing errors on
first shell login.

lib/shell.sh:
  - Defines 13 built-in frameworks with detect + install commands
  - Scans ~/.zshrc / ~/.bashrc etc. for references before installing
    (avoids installing things the user doesn't actually use)
  - SSR_SHELL_DEPS_EXTRA in ssr.conf for custom user additions

bin/ssr-restore:
  - Adds `shell_deps` as a resumable step after mackup_restore
  - Sources ~/.config/ssr/post-restore.sh if present (user hook)

config/post-restore.sh.example:
  - Template with commented examples (OMZ plugins, npm globals, SSH keys)

Co-authored-by: Cursor <cursoragent@cursor.com>

bin/ssr-restore

@@ -23,6 +23,8 @@ source "$SSR_ROOT/lib/macos-prefs.sh"
 source "$SSR_ROOT/lib/restore-state.sh"
 # shellcheck source=../lib/icloud.sh
 source "$SSR_ROOT/lib/icloud.sh"
+# shellcheck source=../lib/shell.sh
+source "$SSR_ROOT/lib/shell.sh"
 
 ssr::require_macos
 ssr::load_config
@@ -100,6 +102,14 @@ ssr::rs::run mackup_restore  "Mackup restore"          _ssr_mackup_restore_step
 # by Mackup (com.apple.dock.plist etc.) without requiring a logout.
 ssr::macos::restart_ui
 
+# After dotfiles are in place, install any shell frameworks / version
+# managers they reference that aren't already present (e.g. Oh My Zsh).
+if [[ "${SSR_SHELL_DEPS_ENABLED:-true}" == "true" ]]; then
+    ssr::rs::run shell_deps  "Shell framework deps"    ssr::shell::detect_and_install
+else
+    ssr::rs::set "step_shell_deps" "skipped"
+fi
+
 ssr::rs::run macos_defaults  "macOS defaults"          ssr::macos::apply_defaults
 
 if [[ "${SSR_SNAPSHOT_MACOS_PREFS:-true}" == "true" ]]; then
@@ -112,6 +122,20 @@ fi
 # resumable step — it's side-effect-only and always safe to re-run).
 ssr::macos::open_installed_casks
 
+# --- User-defined post-restore hook --------------------------------------
+# Sources ~/.config/ssr/post-restore.sh when present.
+# Copy config/post-restore.sh.example from the repo as a starting point.
+_user_hook="${SSR_CONFIG_DIR:-$HOME/.config/ssr}/post-restore.sh"
+if [[ -f "$_user_hook" ]]; then
+    ssr::log "Running post-restore hook: $_user_hook"
+    # shellcheck source=/dev/null
+    source "$_user_hook" \
+        && ssr::ok "post-restore hook completed" \
+        || ssr::warn "post-restore hook exited with errors (non-fatal)"
+else
+    ssr::log "No post-restore hook found (optional: $_user_hook)"
+fi
+
 # Mark overall completion time.
 ssr::rs::set "finished" "$(ssr::ts)"