feat(agents): add qintianjian (observatory) agent for data analysis

[mvanhorn]

Summary / 概要

Add 钦天监 (Imperial Observatory) agent SOUL.md for data analysis, performance metrics, trend prediction, and observability.

Chose 钦天监 because its responsibilities (数据分析、性能度量、趋势预测、可观测性) have zero overlap with the existing 12 agents. 刑部 already covers quality/testing/compliance, and 礼部 already covers documentation.

Changes / 改动

Created agents/qintianjian/SOUL.md following the exact template structure from existing agents:

• Role description matching historical 钦天监 responsibilities (astronomy/observation -> data analysis)
• 4 professional domains: data analysis, performance metrics, trend prediction, observability
• Kanban CLI commands matching the GLOBAL.md contract
• 3 interaction scenarios: API latency investigation, growth forecasting, log anomaly detection
• Collaboration relationships with 工部 (build systems), 刑部 (quality evidence), 户部 (capacity planning)

Acceptance Criteria / 验收标准

• SOUL.md 结构完整，符合现有模板格式
• Agent 职责不与现有 12 个角色重叠
• 包含至少 3 个示例交互场景

Fixes #224

This contribution was developed with AI assistance (Claude Code).