docs(ultraplan-local): document /ultracontinue in README + CLAUDE
- README: version badge 3.2.0 → 3.3.0, "Six commands" intro, /ultracontinue row in command table, full /ultracontinue-local section with modes + schema v1 + /ultraplan-end-session helper + typical flow.
- CLAUDE.md: extend validators list (atomic-write util, session-state-validator), bump test count 109 → 185, "7 pipeline handovers" line, Continue paragraph in Architecture, .session-state.local.json + Continue stats in State, Session-state entry in Terminology.
Step 11 of /ultracontinue v3.3.0.