Add Railway configuration file

This adds a railway.json configuration to help with Railway deployments.
However, the main fix for the build error requires setting DATABASE_TYPE
as a build-time environment variable in Railway's dashboard.

railway.json

@@ -0,0 +1,14 @@
+{
+  "$schema": "https://railway.app/railway.schema.json",
+  "build": {
+    "builder": "DOCKERFILE",
+    "dockerfilePath": "Dockerfile",
+    "buildCommand": null
+  },
+  "deploy": {
+    "numReplicas": 1,
+    "sleepApplication": false,
+    "restartPolicyType": "ON_FAILURE",
+    "restartPolicyMaxRetries": 10
+  }
+}