Add Streamable HTTP transport for remote MCP access

- Convert from stdio-only to dual-mode (stdio + HTTP)
- Add Express server with /mcp endpoint for Streamable HTTP
- Add /health endpoint for Railway health checks
- Update MCP SDK to v1.12.0 for Streamable HTTP support
- Add railway.toml for Railway deployment
- Default to HTTP mode, use --stdio flag for local mode

railway.toml

@@ -0,0 +1,9 @@
+[build]
+builder = "dockerfile"
+dockerfilePath = "Dockerfile"
+
+[deploy]
+healthcheckPath = "/health"
+healthcheckTimeout = 30
+restartPolicyType = "on_failure"
+restartPolicyMaxRetries = 3