refactor(docs): DRY think-tank warnings with centralized procedure

[atxtechbro]

Problem & Solution

Problem: Multiple files contained redundant think-tank warnings after PR #1004, violating DRY principle and creating maintenance burden.
Solution: Replace detailed warnings with concise links to the authoritative think-tank.md procedure, applying "subtraction creates value" principle.
Keywords: DRY, think-tank, subtraction-creates-value, refactor

Related Issues

Builds on #1003, #1004, #1005, #1007

Technical Details

Files changed:

• knowledge/procedures/worktree-workflow.md - Simplified warning to link
• knowledge/procedures/git-workflow.md - Replaced section with link
• knowledge/principles/no-leaks.md - Removed redundant explanation, added link
• knowledge/procedures/think-tank.md - Added from PR docs(procedures): add think-tank directory documentation #1007 for completeness

Key modifications:

• Reduced ~5 lines per location to 1 line
• Centralized authority in think-tank.md
• Maintained discoverability through links

Alternative approaches considered:

• Could remove warnings entirely, but breadcrumbs help discovery
• Links balance brevity with guidance

Testing

• Verify all links point to correct location
• Ensure no loss of critical information

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have added/updated tests that prove my fix is effective or that my feature works (if applicable)
• I have updated the documentation accordingly (if applicable)

[amazon-q-developer]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[amazon-q-developer]

✅ I finished the code review, and didn't find any security or code quality issues.