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)

templates/USER.md

@@ -0,0 +1,29 @@
+# User
+
+name: {{NAME}}
+profession: {{PROFESSION}}
+location: {{LOCATION}}
+timezone: {{TIMEZONE}}
+
+## Demographics
+
+marital status: {{MARITAL_STATUS}}
+age: {{AGE}}
+gender: {{GENDER}}
+education: {{EDUCATION}}
+
+## Skillset
+
+{{SKILLSET}}
+
+## Interests
+
+{{INTERESTS}}
+
+## Hobbies
+
+{{HOBBIES}}
+
+## Pets
+
+{{PETS}}