feat(onboard): user onboarding - no default USER.md, guided creation (#37)

- bootstrap no longer creates user/USER.md (owner direction)
- scripts/onboard.sh: name REQUIRED (interactive loop or --name),
  optional fields prompted (profession, marital, age, gender, education,
  location, timezone, skillset, interests, hobbies, pets); flag-driven
  non-interactive mode for automation
- templates/USER.md: canon skeleton, placeholder rendering, unfilled
  optional = (not provided)
- agent.sh: auto-runs onboarding when profile missing (TTY gate);
  headless run-task warns and continues without user context
- user profile dispatched to all launches (M14 layer)

Closes #37 (onboarding requirements from owner layout review)

scripts/agent.sh

@@ -41,6 +41,14 @@ load_config
 load_release
 bootstrap_runtime_dir
 
+# Onboarding gate (M16): a TUI agent cannot launch without a user profile.
+# The onboarding wizard runs automatically here - the TTY is already yours.
+if [ ! -f "$MOSAIC_DEV_DIR/user/USER.md" ]; then
+    echo "agent: no user profile found - starting onboarding"
+    scripts/onboard.sh
+    [ -f "$MOSAIC_DEV_DIR/user/USER.md" ] || { echo "agent: onboarding did not complete; aborting launch" >&2; exit 1; }
+fi
+
 # Agent seat definition (M15): when agents/<name>/agent.json exists it is
 # strictly validated and its values become defaults (CLI flags override).
 # The seat's SOUL.md overrides the contract persona; governance contracts