fix(skills): inject skill list into system prompt for LLM awareness

Problem: Agent could not invoke appropriate skills when user asked about
financial reports because LLM didn't know which skills were available.

Root causes:
1. System prompt lacked available skill list
2. SkillManifest struct missing 'triggers' field
3. SKILL.md loader not parsing triggers list
4. "财报" keyword not matching "财务报告" trigger

Changes:
- Add triggers field to SkillManifest struct
- Parse triggers list from SKILL.md frontmatter
- Inject skill list into system prompt in kernel.rs
- Add "财报", "财务数据", "盈利", "营收" triggers to finance-tracker
- Add "财报分析" trigger to analytics-reporter
- Document fix in troubleshooting.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/analytics-reporter/SKILL.md

@@ -9,6 +9,8 @@ triggers:
   - "业务洞察"
   - "KPI追踪"
   - "预测分析"
+  - "财报分析"
+  - "数据报表"
 tools:
   - bash
   - read