cleanup: remove orphan algorithm modules (#993)

[TATP-233]

Summary

• delete the unreferenced and unexported BaseCollector module
• delete the unreferenced and unexported FastTD3Runner module
• add a repo-hygiene regression for the two removed orphan paths

Validation

• make test-all passed at 7c7e50a6decd6168ed3b2c6e31ecd51539eaad35
• 1673 passed, 27 skipped, 273 deselected, 1 xfailed
• benchmark smoke: 33/34 module-mode and 34/35 script-mode; MLX-only entries skipped
• full-tree reference search found no consumer, export, registry, config, test, benchmark, or docs reference

Closes #993