fix: Use lowercase 'dockerfile' builder in railway.toml

Railway may be case-sensitive on the builder type.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: silversurfer562

railway.toml

@@ -1,5 +1,5 @@
 [build]
-builder = "DOCKERFILE"
+builder = "dockerfile"
 dockerfilePath = "Dockerfile"
 
 [deploy]