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>

crates/zclaw-skills/src/skill.rs

@@ -32,6 +32,9 @@ pub struct SkillManifest {
     /// Tags for categorization
     #[serde(default)]
     pub tags: Vec<String>,
+    /// Trigger words for skill activation
+    #[serde(default)]
+    pub triggers: Vec<String>,
     /// Whether the skill is enabled
     #[serde(default = "default_enabled")]
     pub enabled: bool,