Fix: Honor output directory for selected reports

[elohmeier]

Summary

• pass --output-dir through the exact --report and regex --reports paths
• share output-directory normalization between full and selected report generation
• cover both selectors through the real Tj3 CLI class

Validation

• 111 unit tests, 262,170 assertions
• 72 specification examples
• exact report selection writes HTML and support assets to the requested directory
• regex report selection writes HTML and support assets to the requested directory
• both process working directories remain empty