feat: add triggers to all 38 skill templates

Multi-word, skill-specific trigger keywords for GBrain's RESOLVER.md
router. Each skill gets 3-6 triggers derived from its "Use when asked
to..." description text. Avoids single generic words that would collide
across skills (e.g., "debug this" not "debug").

These are distinct from voice-triggers (speech-to-text aliases) and
serve GBrain's checkResolvable() validation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gstack-upgrade/SKILL.md.tmpl

@@ -10,6 +10,10 @@ voice-triggers:
   - "update the tools"
   - "gee stack upgrade"
   - "g stack upgrade"
+triggers:
+  - upgrade gstack
+  - update gstack version
+  - get latest gstack
 allowed-tools:
   - Bash
   - Read