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

skills/git-workflow/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: git-workflow
-description: Git workflow best practices — commit conventions, branching strategies, PR conventions, rebase vs merge, and code review. Use when writing commit messages, reviewing PRs, planning branching strategy, or whenever the user mentions "commit," "branch," "pull request," "PR," "merge," "rebase," "squash," "git flow," "trunk-based," "conventional commit," or "code review."
+description: Git workflow best practices — commit conventions, branching strategies, PR conventions, rebase vs merge, and code review. Use when writing commit messages, reviewing PRs, planning branching strategy. Detects from code context and project files — not dependent on specific language keywords."
 ---
 
 # Git Workflow