fix: drop unsupported buildContext/dockerfilePath from mcp railway.json

CodeRabbit flagged buildContext as unsupported. Confirmed against Railway's
config schema: supported build keys are builder, watchPatterns, buildCommand,
dockerfilePath, railpackVersion. buildContext was silently ignored. Railway sets
the Docker build context via the service Root Directory, not a config key, so the
MCP service must set Root Directory=mcp-server in the dashboard; with that, the
context is mcp-server/ and the Dockerfile is auto-detected, so dockerfilePath is
dropped too (a repo-root-relative path is wrong inside the restricted context).
Keeps only supported keys + the deploy healthcheck block.

Author: DevanshuNEU

mcp-server/railway.json

@@ -1,9 +1,7 @@
 {
   "$schema": "https://railway.app/railway.schema.json",
   "build": {
-    "builder": "DOCKERFILE",
-    "dockerfilePath": "mcp-server/Dockerfile",
-    "buildContext": "mcp-server"
+    "builder": "DOCKERFILE"
   },
   "deploy": {
     "restartPolicyType": "ON_FAILURE",