feat: add workflow-tune skill for multi-step workflow pipeline optimization

New skill that executes workflow step chains sequentially, inspects artifacts,
analyzes quality via ccw cli resume chain (Gemini), and generates optimization
reports. Supports 4 input formats: pipe-separated commands, comma-separated
skills, JSON file, and natural language with semantic decomposition.

Key features:
- Orchestrator + 5-phase progressive loading architecture
- Intent-to-tool mapping with ambiguity resolution for NL input
- Command document generation with pre-execution confirmation loop
- Per-step analysis + cross-step synthesis via resume chain
- Auto-fix with user confirmation safety gate

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/skills/workflow-tune/templates/synthesis-prompt.md

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+# Synthesis Prompt Template
+
+Phase 04 使用此模板构造 ccw cli 提示词，让 Gemini 综合所有步骤分析，产出跨步骤优化建议。
+
+## Template
+
+```
+PURPOSE: Synthesize all step analyses into a holistic workflow optimization assessment. Evaluate cross-step concerns: ordering, handoff quality, redundancy, bottlenecks, and overall workflow coherence.
+
+WORKFLOW OVERVIEW:
+Name: ${workflowName}
+Goal: ${workflowContext}
+Steps: ${stepCount}
+Average Quality: ${avgScore}/100
+Weakest Step: ${minScore}/100
+Total Issues: ${totalIssues} (${totalHighIssues} high severity)
+
+SCORE SUMMARY:
+${scoreSummary}
+
+COMPLETE PROCESS LOG:
+${processLog}
+
+DETAILED STEP ANALYSES:
+${stepAnalyses}
+
+TASK:
+1. **Workflow Coherence**: Do steps form a logical sequence? Any missing steps?
+2. **Handoff Quality**: Are step outputs well-consumed by subsequent steps? Data format mismatches?
+3. **Redundancy Detection**: Do any steps duplicate work? Overlapping concerns?
+4. **Bottleneck Identification**: Which steps are bottlenecks (lowest quality, longest duration)?
+5. **Step Ordering**: Would reordering steps improve outcomes?
+6. **Missing Steps**: Are there gaps in the pipeline that need additional steps?
+7. **Per-Step Optimization**: Top 3 improvements per underperforming step
+8. **Workflow-Level Optimization**: Structural changes to the overall pipeline
+
+EXPECTED OUTPUT (strict JSON, no markdown):
+{
+  "workflow_score": <0-100>,
+  "coherence": {
+    "score": <0-100>,
+    "assessment": "<logical flow evaluation>",
+    "gaps": ["<missing step or transition>"]
+  },
+  "handoff_quality": {
+    "score": <0-100>,
+    "issues": [
+      { "from_step": "<step name>", "to_step": "<step name>", "issue": "<description>", "fix": "<suggestion>" }
+    ]
+  },
+  "redundancy": {
+    "found": <true|false>,
+    "items": [
+      { "steps": ["<step1>", "<step2>"], "description": "<what overlaps>", "recommendation": "<merge or remove>" }
+    ]
+  },
+  "bottlenecks": [
+    { "step": "<step name>", "reason": "<why it's a bottleneck>", "impact": "high|medium|low", "fix": "<suggestion>" }
+  ],
+  "ordering_suggestions": [
+    { "current": "<current order description>", "proposed": "<new order>", "rationale": "<why>" }
+  ],
+  "per_step_improvements": [
+    { "step": "<step name>", "improvements": [
+      { "priority": "high|medium|low", "description": "<what to change>", "rationale": "<why>" }
+    ]}
+  ],
+  "workflow_improvements": [
+    { "priority": "high|medium|low", "category": "structure|handoff|performance|quality", "description": "<change>", "rationale": "<why>", "affected_steps": ["<step names>"] }
+  ],
+  "summary": "<2-3 sentence executive summary of workflow health and top recommendations>"
+}
+
+CONSTRAINTS: Be specific, reference step names and artifact details, output ONLY JSON
+```
+
+## Variable Substitution
+
+| Variable | Source | Description |
+|----------|--------|-------------|
+| `${workflowName}` | workflow-state.json | Workflow 名称 |
+| `${workflowContext}` | workflow-state.json | Workflow 目标 |
+| `${stepCount}` | workflow-state.json | 总步骤数 |
+| `${avgScore}` | Phase 04 computes | 所有步骤平均分 |
+| `${minScore}` | Phase 04 computes | 最低步骤分 |
+| `${totalIssues}` | Phase 04 computes | 总问题数 |
+| `${totalHighIssues}` | Phase 04 computes | 高优先级问题数 |
+| `${scoreSummary}` | Phase 04 builds | 每步分数一行 |
+| `${processLog}` | process-log.md | 完整过程日志 |
+| `${stepAnalyses}` | Phase 04 reads | 所有 step-N-analysis.md 内容 |