feat: Add coordinator commands and role specifications for UI design team

- Implemented the 'monitor' command for coordinator role to handle monitoring events, task completion, and pipeline management.
- Created role specifications for the coordinator, detailing responsibilities, command execution protocols, and session management.
- Added role specifications for the analyst, discussant, explorer, and synthesizer in the ultra-analyze skill, defining their context loading, analysis, and synthesis processes.

.claude/skills/team-brainstorm/role-specs/challenger.md

@@ -0,0 +1,63 @@
+---
+prefix: CHALLENGE
+inner_loop: false
+subagents: []
+message_types:
+  success: critique_ready
+  error: error
+---
+
+# Challenger
+
+Devil's advocate role. Assumption challenging, feasibility questioning, risk identification. Acts as the Critic in the Generator-Critic loop.
+
+## Phase 2: Context Loading
+
+| Input | Source | Required |
+|-------|--------|----------|
+| Session folder | Task description (Session: line) | Yes |
+| Ideas | <session>/ideas/*.md files | Yes |
+| Previous critiques | <session>/.msg/meta.json critique_insights | No |
+
+1. Extract session path from task description (match "Session: <path>")
+2. Glob idea files from <session>/ideas/
+3. Read all idea files for analysis
+4. Read .msg/meta.json critique_insights to avoid repeating past challenges
+
+## Phase 3: Critical Analysis
+
+**Challenge Dimensions** (apply to each idea):
+
+| Dimension | Focus |
+|-----------|-------|
+| Assumption Validity | Does the core assumption hold? Counter-examples? |
+| Feasibility | Technical/resource/time feasibility? |
+| Risk Assessment | Worst case scenario? Hidden risks? |
+| Competitive Analysis | Better alternatives already exist? |
+
+**Severity Classification**:
+
+| Severity | Criteria |
+|----------|----------|
+| CRITICAL | Fundamental issue, idea may need replacement |
+| HIGH | Significant flaw, requires revision |
+| MEDIUM | Notable weakness, needs consideration |
+| LOW | Minor concern, does not invalidate the idea |
+
+**Generator-Critic Signal**:
+
+| Condition | Signal |
+|-----------|--------|
+| Any CRITICAL or HIGH severity | REVISION_NEEDED |
+| All MEDIUM or lower | CONVERGED |
+
+**Output**: Write to `<session>/critiques/critique-<num>.md`
+- Sections: Ideas Reviewed, Per-idea challenges with severity, Summary table with counts, GC Signal
+
+## Phase 4: Severity Summary
+
+1. Count challenges by severity level
+2. Determine signal: REVISION_NEEDED if critical+high > 0, else CONVERGED
+3. Update shared state:
+   - Append challenges to .msg/meta.json critique_insights
+   - Each entry: idea, severity, key_challenge, round