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/schema.prisma

@@ -60,6 +60,8 @@ model City {
   riskLevel       Int
   policePressure  Float    @default(1.0)
   economyModifier Float    @default(1.0)
+  mapX            Float    @default(50)
+  mapY            Float    @default(50)
   createdAt       DateTime @default(now())
 
   players  Player[]
@@ -77,9 +79,10 @@ model Item {
   weight       Int      @default(1)
   createdAt    DateTime @default(now())
 
-  inventory InventoryItem[]
-  prices    MarketPrice[]
-  missions  Mission[]
+  inventory          InventoryItem[]
+  prices             MarketPrice[]
+  requiredInMissions Mission[]       @relation("MissionRequiredItem")
+  rewardInMissions   Mission[]       @relation("MissionRewardItem")
 }
 
 model InventoryItem {
@@ -112,19 +115,24 @@ model Mission {
   id                   String      @id @default(uuid())
   cityId               String
   title                String
+  description          String      @default("")
   type                 MissionType
   difficulty           Int
+  minLevel             Int         @default(1)
   durationSeconds      Int
   rewardMoney          Int
   rewardXp             Int
   risk                 Float
   requiredItemId       String?
   requiredItemQuantity Int?
+  rewardItemId         String?
+  rewardItemQuantity   Int?
   expiresAt            DateTime
   createdAt            DateTime    @default(now())
 
   city           City            @relation(fields: [cityId], references: [id])
-  requiredItem   Item?           @relation(fields: [requiredItemId], references: [id])
+  requiredItem   Item?           @relation("MissionRequiredItem", fields: [requiredItemId], references: [id])
+  rewardItem     Item?           @relation("MissionRewardItem", fields: [rewardItemId], references: [id])
   playerMissions PlayerMission[]
 }