- Migration 20: collapse `Nairobi`/`nairobi` in domain.vehicles → 'nairobi'
- Remove the SLO panel from the top band (filter + tile rows stay)
- Offline vehicles render as solid grey instead of dim-cost-centre tint;
opacity now only differentiates moving (1.0) vs parked (0.75) vs
offline (0.55) so colour carries identity + state cleanly
