[codex] remove fixed test count gates

[kachofugetsu09]

Summary

• remove the hard-coded 1080 Python test budget, retained-file manifest, and 62 Web test count assertion
• keep CI running the repository's actual Python tests and make the Web runner discover .test.mjs files from the source roots
• fix three ESLint errors in kaomoji-markdown without changing matching behavior
• document the current test-selection contract and recovery point

Why

The fixed counts turned a historical cleanup snapshot into a false CI contract. The current Web suite has 56 tests, so the old 62-test assertion rejected the real suite. Test retention now follows observable regressions, invariants, boundaries, and concrete bugs.

Checks

• npm ci --no-audit --no-fund
• npm run test:web (56 passed)
• npm run typecheck
• npm run lint (0 errors; 42 existing warnings)
• .venv/bin/pytest -q tests/ (1075 passed, 5 skipped)
• SDK pyright and pytest (11 passed)
• Python pyright and control schema check
• change-impact Gate passed: docker/debug/reports/change-gate/20260904-121135-04ec73d2