feat: add versioned migrations and kysely query layer

backend/migrations/1700000002000_create-user-preferences.cjs

@@ -0,0 +1,24 @@
+exports.up = (pgm) => {
+  pgm.createTable('user_preferences', {
+    user_id: {
+      type: 'uuid',
+      primaryKey: true,
+      notNull: true,
+      references: 'users(id)',
+      onDelete: 'CASCADE',
+    },
+    preferred_pace: { type: 'text' },
+    preferred_budget_level: { type: 'text' },
+    max_walking_distance_km: { type: 'numeric' },
+    preferred_start_time: { type: 'text' },
+    child_friendly_preferred: { type: 'boolean', notNull: true, default: false },
+    interests: { type: 'text[]', notNull: true, default: '{}' },
+    notes: { type: 'text' },
+    created_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
+    updated_at: { type: 'timestamptz', notNull: true, default: pgm.func('now()') },
+  });
+};
+
+exports.down = (pgm) => {
+  pgm.dropTable('user_preferences');
+};