Align skill docs and career sheet guidance

[unagi]

Summary

• align SKILL.md guidance and output naming with current behavior and UTC timestamps
• update career_sheet_best_practices structure and sample references to match actual outputs
• move layout schema to tools/schema and refresh related docs/tests

Testing

• uv run poe check-all

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.96%. Comparing base (aa1eec9) to head (d948331).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #26      +/-   ##
==========================================
+ Coverage   90.47%   90.96%   +0.48%     
==========================================
  Files          22       22              
  Lines        1922     1936      +14     
==========================================
+ Hits         1739     1761      +22     
+ Misses        183      175       -8     

Flag	Coverage Δ
unittests	90.96% <100.00%> (+0.48%)	⬆️

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud