Add Brenner-style linting (filter weak inferences before triage)

[brycejohnson1417]

Summary

• Add heuristic linting rules inspired by BrennerBot (discriminability, third alternative, validity checks).
• Skip low-quality inference candidates during /api/process so the triage queue stays high-signal.

Why

• Prevents trivial/non-falsifiable inferences from wasting human review time.

Notes

• This is intentionally conservative; future work can store lint failures separately for analytics.