[solo applicant] avoid duplicate evaluation when a second tab asks for the same evaluation

Proof set for Evaluate fit (boolean criterion changes after eval — single-flight prevents re-eval)

Pin G4 commute: workspace home address is the origin Google Routes computeRoutes uses to fill the commute cell; and when a second client opens an already-hydrated job, compute_lock holds the singleflight and prevents a re-evaluation, returning {locked:true} without re-firing the Maps call.