server: schema — City map coords, Mission narrative/level/loot fields

Add mapX/mapY to City for SVG map positioning; add description,
minLevel, rewardItemId/Quantity to Mission; add named relations
MissionRequiredItem and MissionRewardItem on Item. Seed updated
with Italian city coordinates.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/prisma/seed.ts

@@ -4,13 +4,16 @@ import { randomFloat } from '../src/shared/validators.js';
 
 const prisma = new PrismaClient();
 
-/** Città iniziali (blueprint §19): economia e rischio differenziati. */
+/**
+ * Città iniziali (blueprint §19): economia e rischio differenziati.
+ * mapX/mapY sono coordinate percentuali (0-100) sulla mappa stilizzata dell'Italia.
+ */
 const CITIES = [
-  { name: 'Milano', riskLevel: 3, policePressure: 1.1, economyModifier: 1.25 },
-  { name: 'Napoli', riskLevel: 4, policePressure: 1.3, economyModifier: 1.0 },
-  { name: 'Palermo', riskLevel: 4, policePressure: 1.25, economyModifier: 0.85 },
-  { name: 'Torino', riskLevel: 2, policePressure: 0.9, economyModifier: 1.0 },
-  { name: 'Bari', riskLevel: 3, policePressure: 1.0, economyModifier: 0.85 },
+  { name: 'Milano', riskLevel: 3, policePressure: 1.1, economyModifier: 1.25, mapX: 32, mapY: 12 },
+  { name: 'Napoli', riskLevel: 4, policePressure: 1.3, economyModifier: 1.0, mapX: 60, mapY: 58 },
+  { name: 'Palermo', riskLevel: 4, policePressure: 1.25, economyModifier: 0.85, mapX: 52, mapY: 86 },
+  { name: 'Torino', riskLevel: 2, policePressure: 0.9, economyModifier: 1.0, mapX: 16, mapY: 16 },
+  { name: 'Bari', riskLevel: 3, policePressure: 1.0, economyModifier: 0.85, mapX: 78, mapY: 52 },
 ];
 
 /** Item commerciabili iniziali (blueprint §19). */
@@ -32,6 +35,8 @@ async function main(): Promise<void> {
         riskLevel: city.riskLevel,
         policePressure: city.policePressure,
         economyModifier: city.economyModifier,
+        mapX: city.mapX,
+        mapY: city.mapY,
       },
     });
   }