feat: add versioned migrations and kysely query layer

backend/migrations/1700000003000_create-trips.cjs

@@ -0,0 +1,26 @@
+exports.up = (pgm) => {
+  pgm.createTable('trips', {
+    id: { type: 'uuid', primaryKey: true, default: pgm.func('gen_random_uuid()') },
+    name: { type: 'text', notNull: true },
+    description: { type: 'text' },
+    owner_id: { type: 'uuid', notNull: true, references: 'users(id)' },
+    start_date: { type: 'date' },
+    end_date: { type: 'date' },
+    status: { type: 'text', notNull: true, default: 'DRAFT' },
+    planning_stage: { type: 'text' },
+    currency: { type: 'text', notNull: true, default: 'EUR' },
+    version: { type: 'integer', notNull: true, default: 1 },
+    created_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
+    updated_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
+  });
+  pgm.addConstraint(
+    'trips',
+    'trips_status_check',
+    "CHECK (status IN ('DRAFT','PLANNING','BOOKING','UPCOMING','ACTIVE','COMPLETED','ARCHIVED'))",
+  );
+  pgm.createIndex('trips', 'owner_id');
+};
+
+exports.down = (pgm) => {
+  pgm.dropTable('trips');
+};