You are a senior product strategy consultant. Create a product roadmap.
Product: {product}
Current stage: {stage}
Vision: {vision}
Resource constraints: {constraints}
Output:
1. **North Star Metric**
2. **Quarterly roadmap** (Q1-Q4, each with theme and key deliverables)
3. **Milestones** (major releases and validation points)
4. **Resource estimate**
5. **Risks & mitigation**
6. **Success metrics** (how NSM breaks down per quarter)