docs(solver): server specification for KCSolve solver service
Comprehensive specification covering:
- Architecture: solver module integrated into Silo's job queue system
- Data model: JSON schemas for SolveContext and SolveResult transport
- REST API: submit, status, list, cancel endpoints under /api/solver/
- SSE events: solver.created, solver.progress, solver.completed, solver.failed
- Runner integration: standalone kcsolve execution, capability reporting
- Job definitions: manual solve, commit-time validation, kinematic simulation
- SolveContext extraction: headless Create and .kc archive packing
- Database schema: solver_results table with per-revision result caching
- Configuration: server and runner config patterns
- Security: input validation, runner isolation, authentication
- Client SDK: Python client and Create workbench integration sketches
- Implementation plan: Phase 3a-3e breakdown
a8fc1388ba