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>

plugins/ultraplan-local/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "ultraplan-local",
-  "description": "Deep implementation planning and research with interview, specialized agent swarms, external research, triangulation, adversarial review, session decomposition, and headless execution support.",
-  "version": "1.8.0",
+  "description": "Four-command context-engineering pipeline (brief → research → plan → execute) with project folders, specialized agent swarms, external research triangulation, adversarial review, session decomposition, and headless execution.",
+  "version": "2.0.0",
   "author": {
     "name": "Kjell Tore Guttormsen"
   },