Add dependency management to issue workflows

Updated skills and commands to identify and formally link issue
dependencies using tea CLI:

Skills updated:
- issue-writing: Document deps in description + link with tea CLI
- backlog-grooming: Check for formal dependency links in checklist
- roadmap-planning: Link dependencies after creating issues

Commands updated:
- create-issue: Ask about and link dependencies for new issues
- plan-issues: Create in dependency order, link with tea issues deps add
- groom: Check dependency status, suggest missing links

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

skills/roadmap-planning/SKILL.md

@@ -80,6 +80,13 @@ In issue descriptions:
 - Depends on #13 (API setup)
 ```
 
+After creating issues, formally link dependencies:
+```bash
+tea issues deps add <issue> <blocker>
+tea issues deps add 14 12    # Issue #14 depends on #12
+tea issues deps add 14 13    # Issue #14 depends on #13
+```
+
 ## Creating Issues
 
 Use the gitea skill for issue operations.