fix(roads): replace ON CONFLICT with delete and insert for bulletproof candidate approval

apps/api/src/maps/road-refinement.controller.ts

@@ -227,19 +227,15 @@ export class RoadRefinementController {
         CREATE UNIQUE INDEX IF NOT EXISTS approved_roads_cand_uidx ON approved_roads(candidate_id) WHERE candidate_id IS NOT NULL;
       `);
 
-      // 2. Direct insert/upsert into approved_roads immediately
+      // 2. Direct insert into approved_roads immediately (Delete existing first to ensure idempotency)
       await this.dataSource.query(`
+        DELETE FROM approved_roads WHERE candidate_id = $1::uuid;
         INSERT INTO approved_roads (
           candidate_id, geometry, name, highway, confidence, "uniqueDriverCount", oneway, approved_at
         )
         SELECT 
           id, geometry::geometry, COALESCE(name, 'Unnamed Road'), COALESCE(highway, 'residential'), confidence, "uniqueDriverCount", COALESCE(oneway, 0), NOW()
-        FROM candidate_roads WHERE id = $1
-        ON CONFLICT (candidate_id) DO UPDATE SET
-          geometry = EXCLUDED.geometry,
-          name = EXCLUDED.name,
-          highway = EXCLUDED.highway,
-          confidence = EXCLUDED.confidence;
+        FROM candidate_roads WHERE id = $1::uuid;
       `, [id]);
 
       // 3. Mark candidate as approved