v7: clear stale route cache on seed version change; DELETE+INSERT seeds

Fix NH-44 south coords: road goes via Kovilpatti, not Rajapalayam

Fix pass logic: always merge Pass1+Pass2; fix Madurai-south coords

Fix stale routes, fill south India gaps, extend cache to 90 days

Add full India highway coverage — 67 new seed plazas across 9 highways

Add Chennai→Madurai plazas and fix corridor matching

Add US toll plaza seeds and fix 0-plaza bug for United States routes

Fix 0 toll plazas: three-pass spatial strategy with 2000m seed buffer

Fix 0 toll plazas and improve routing