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/specs/workflow-eval-criteria.md

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+# Workflow Evaluation Criteria
+
+Workflow 调优评估标准，由 Phase 03 (Analyze Step) 和 Phase 04 (Synthesize) 引用。
+
+## Per-Step Dimensions
+
+| Dimension | Description |
+|-----------|-------------|
+| Execution Success | 命令是否成功执行，退出码是否正确 |
+| Output Completeness | 产物是否齐全，预期文件是否生成 |
+| Artifact Quality | 产物内容质量 — 非空、格式正确、内容有意义 |
+| Handoff Readiness | 产物是否满足下一步的输入要求，格式兼容性 |
+
+## Per-Step Scoring Guide
+
+| Range | Level | Description |
+|-------|-------|-------------|
+| 90-100 | Excellent | 执行完美，产物高质量，下游可直接消费 |
+| 80-89 | Good | 执行成功，产物基本完整，微调即可衔接 |
+| 70-79 | Adequate | 执行成功但产物有缺失或质量一般 |
+| 60-69 | Needs Work | 部分失败或产物质量差，衔接困难 |
+| 0-59 | Poor | 执行失败或产物无法使用 |
+
+## Workflow-Level Dimensions
+
+| Dimension | Description |
+|-----------|-------------|
+| Coherence | 步骤间的逻辑顺序是否合理，是否形成完整流程 |
+| Handoff Quality | 步骤间的数据传递是否顺畅，格式是否匹配 |
+| Redundancy | 是否存在步骤间的工作重叠或重复 |
+| Efficiency | 整体流程是否高效，有无不必要的步骤 |
+| Completeness | 是否覆盖所有必要环节，有无遗漏 |
+
+## Analysis Depth Profiles
+
+### Quick
+- 每步 3-5 要点
+- 关注: 执行成功、产出完整、明显问题
+- 跨步骤: 基本衔接检查
+
+### Standard
+- 每步详细评估
+- 关注: 执行质量、产出完整性、产物质量、衔接就绪度、潜在问题
+- 跨步骤: 衔接质量、冗余检测、瓶颈识别
+
+### Deep
+- 每步深度审查
+- 关注: 执行质量、产出正确性、结构质量、衔接完整性、错误处理、性能信号、架构影响、边界情况
+- 跨步骤: 全面流程优化、重排建议、缺失步骤检测、架构改进
+
+## Issue Severity Guide
+
+| Severity | Description | Example |
+|----------|-------------|---------|
+| High | 阻断流程或导致错误结果 | 步骤执行失败、产物格式不兼容、关键数据丢失 |
+| Medium | 影响质量但不阻断 | 产物不完整、衔接需手动调整、冗余步骤 |
+| Low | 可改进但不影响功能 | 输出格式不一致、可优化的步骤顺序 |