feat(ultraplan-local)!: v2.0.0 — brief-driven four-command pipeline

Extract interview from /ultraplan-local into new /ultrabrief-local command.
/ultraplan-local now requires --brief or --project (breaking). All pipeline
artifacts land in one project directory: .claude/projects/{date}-{slug}/
with brief.md, research/, plan.md, sessions/, progress.json.

Breaking changes:
- /ultraplan-local requires --brief <path> or --project <dir>
- /ultraplan-local --spec removed (convert specs to briefs per MIGRATION.md)
- Interview phase moved to /ultrabrief-local
- spec-reviewer renamed to brief-reviewer with 5th dimension (Research Plan validity)

Added:
- /ultrabrief-local command (interactive interview → brief.md with research plan)
- templates/ultrabrief-template.md (task brief format with intent + research plan)
- brief-reviewer agent (5-dimension brief quality review)
- --project <dir> flag on /ultraresearch-local, /ultraplan-local, /ultraexecute-local
- MIGRATION.md (v1 → v2 upgrade guide)

Changed:
- planning-orchestrator accepts Brief file: input (was Spec file:)
- planning-orchestrator Phase 1b uses brief-reviewer
- README + CLAUDE.md rewritten for four-command pipeline and task/research brief terminology
- CHANGELOG.md [2.0.0] entry with rationale
- Marketplace root README + CLAUDE.md updated to v2.0.0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CLAUDE.md

@@ -12,7 +12,7 @@ plugins/
   llm-security/          v6.0.0  — Security scanning, auditing, threat modeling
   ms-ai-architect/       v1.8.0  — Microsoft AI architecture (Cosmo Skyberg persona)
   okr/                   v1.0.0  — OKR guidance for Norwegian public sector
-  ultraplan-local/       v1.6.0  — Deep planning, research, execution
+  ultraplan-local/       v2.0.0  — Brief, research, plan, execute (four-command pipeline)
 ```
 
 Hvert plugin er selvstendig med egen CLAUDE.md, README, hooks, agents og commands.