Add lagged/tier/prod-subset/mom-conditional checks on research.sqlite.
Log: unconditional sign is a winner/bleeder tug-of-war; mom-conditional
fip stays negative and reliable; warn on high-vol tilt if universe broadens.
Add research-only snapshot extender, PIT dollar-volume mask for signal IC,
rank-only harness path, fingerprint+breadth runner, and docs. Fingerprint
reproduced IC -0.045 / t -2.91 on prod.sqlite. No production gate/schedule changes.