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/finance-tracker/SKILL.md

@@ -6,9 +6,14 @@ triggers:
   - "预算管理"
   - "现金流"
   - "财务报告"
+  - "财报"
   - "投资分析"
   - "成本优化"
   - "财务规划"
+  - "财务数据"
+  - "盈利"
+  - "营收"
+  - "利润"
 tools:
   - bash
   - read