Blueprint Template (Full, >5 tasks)

# Build Blueprint vX.Y | Status: draft/confirmed/executing/frozen
- Date / Branch / Linked requirement
## 1. Goals & Non-Goals
## 2. Success Criteria
## 3. Technical Approach (primary + fallback + one-line reason each)
## 4. Milestones M1/M2/M3 (each with exit criteria)
## 5. Task List
- [ ] S1-T1 <task> | Acceptance: ... | M1
## 6. Acceptance Criteria
## 7. Risks & Assumptions
## 8. Change Log
- v1.1 <date> L2 <task>: <why> -> <impact>