chore: gitignore top-level railway.toml (#4)

Canonical copy lives in deploy/railway/. Prevents accidental commits
of local copies placed at root for deployment.

Author: ethanj

.gitignore

@@ -49,3 +49,6 @@ coverage/
 
 # NPM configuration (contains auth tokens)
 .npmrc
+
+# Platform-specific deploy configs (canonical copies live in deploy/)
+railway.toml