Initial commit: Fahrrad Verschleißteile Tracker

- Next.js SPA mit Bun Runtime
- Prisma mit SQLite Datenbank
- Vollständige CRUD-Operationen für Fahrräder, Verschleißteile und Wartungshistorie
- Warnsystem für bevorstehende Wartungen
- Statistik-Features (Gesamtkosten, durchschnittliche Lebensdauer)
- Zod-Validierung für alle API-Requests
- Umfassende Test-Suite (41 Tests)

prisma/schema.prisma

@@ -0,0 +1,55 @@
+// This is your Prisma schema file,
+// learn more about it in the docs: https://pris.ly/d/prisma-schema
+
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = "file:./dev.db"
+}
+
+model Bike {
+  id           String     @id @default(cuid())
+  name         String
+  brand        String?
+  model        String?
+  purchaseDate DateTime?
+  notes        String?
+  wearParts    WearPart[]
+  createdAt    DateTime   @default(now())
+  updatedAt    DateTime   @updatedAt
+}
+
+model WearPart {
+  id                String              @id @default(cuid())
+  bikeId            String
+  bike              Bike                 @relation(fields: [bikeId], references: [id], onDelete: Cascade)
+  type              String               // CHAIN, BRAKE_PADS, TIRE, CASSETTE, CHAINRING, DERAILLEUR, etc.
+  brand             String?
+  model             String?
+  installDate       DateTime
+  installMileage    Int                  @default(0)
+  serviceInterval   Int                  // in km
+  status            String               @default("ACTIVE") // ACTIVE, NEEDS_SERVICE, REPLACED, INACTIVE
+  cost              Float?
+  notes             String?
+  maintenanceHistory MaintenanceHistory[]
+  createdAt         DateTime             @default(now())
+  updatedAt         DateTime             @updatedAt
+}
+
+model MaintenanceHistory {
+  id         String        @id @default(cuid())
+  wearPartId String
+  wearPart   WearPart      @relation(fields: [wearPartId], references: [id], onDelete: Cascade)
+  date       DateTime
+  mileage    Int
+  action     String        // INSTALL, REPLACE, SERVICE, CHECK, ADJUST
+  notes      String?
+  cost       Float?
+  createdAt  DateTime      @default(now())
+  updatedAt  DateTime      @updatedAt
+}
+