feat(hub-guide): language-agnostic auto-trigger across all skills

- Add principle 27: 'Language-Agnostic Auto-Trigger' to engineering-principles
- Remove hardcoded English-only keyword lists from all 26 skill descriptions
- Replace with concept-based detection: triggers from code context, project files,
  and file types regardless of spoken language
- Update detect-project.sh hook output with language-agnostic message

hooks/scripts/detect-project.sh

@@ -74,3 +74,4 @@ if [ -n "$SKILLS" ]; then
 fi
 echo "📐 [hub-guide] Apply these best-practice rules throughout this session."
 echo "📐 [hub-guide] When in doubt about intent or approach — ask instead of assuming."
+echo "📐 [hub-guide] All skills work regardless of your spoken language — they trigger from code context and project files, not just English keywords."