feat(14-01): create gsd-researcher agent with research methodology
- 4 research modes: ecosystem, feasibility, implementation, comparison
- Tool strategy with Context7 > Official docs > WebSearch hierarchy
- Source hierarchy with HIGH/MEDIUM/LOW confidence levels
- Complete verification protocol with known pitfalls
- Output formats for phase research, project research, comparisons
- Execution flow and structured returns to orchestrator
902 lines consolidated from ~1,200 lines of source material (25% reduction)