feat: add issue-grounded ideation mode to ce:ideate

New issue-intelligence-analyst agent that fetches GitHub issues via
gh CLI, clusters by root-cause themes, and returns structured analysis
with trend direction, confidence scores, and source mix. Designed for
both ce:ideate integration and standalone use.

Agent design:
- Priority-aware fetching with label scanning for focus targeting
- Truncated bodies (500 chars) in initial fetch to avoid N+1 calls
- Single gh call per fetch, no pipes or scripts (avoids permission spam)
- Built-in --jq for all field extraction and filtering
- Mandatory structured output with self-check checklist
- Accurate counts from actual data, not assumptions
- Closed issues as recurrence signal only, not standalone evidence

ce:ideate gains:
- Issue-tracker intent detection in Phase 0.2
- Conditional agent dispatch in Phase 1 (parallel with existing scans)
- Dynamic frame derivation from issue clusters in Phase 2
- Hybrid strategy: cluster-derived frames + default padding when < 4
- Resume awareness distinguishing issue vs non-issue ideation
- Numbered table format for rejection summary in ideation artifacts

plugins/compound-engineering/README.md

@@ -6,7 +6,7 @@ AI-powered development tools that get smarter with every use. Make each unit of
 
 | Component | Count |
 |-----------|-------|
-| Agents | 28 |
+| Agents | 29 |
 | Commands | 23 |
 | Skills | 20 |
 | MCP Servers | 1 |
@@ -35,13 +35,14 @@ Agents are organized into categories for easier discovery.
 | `schema-drift-detector` | Detect unrelated schema.rb changes in PRs |
 | `security-sentinel` | Security audits and vulnerability assessments |
 
-### Research (5)
+### Research (6)
 
 | Agent | Description |
 |-------|-------------|
 | `best-practices-researcher` | Gather external best practices and examples |
 | `framework-docs-researcher` | Research framework documentation and best practices |
 | `git-history-analyzer` | Analyze git history and code evolution |
+| `issue-intelligence-analyst` | Analyze GitHub issues to surface recurring themes and pain patterns |
 | `learnings-researcher` | Search institutional learnings for relevant past solutions |
 | `repo-research-analyst` | Research repository structure and conventions |