Fix tools visibility - revert to v0.1.6 authentication approach

- Disable issuer validation in BearerAuthProvider (issuer=None)
- Simplify authentication condition (remove auth_enabled check)
- Revert CORS middleware to simple configuration
- Fix OAuth metadata endpoint to match v0.1.6
- Apply conditional auth only to MCP server creation

Critical fixes for Claude AI tools discovery

saidsurucu-yargi-mcp-f5fa007/railway.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://railway.app/railway.schema.json",
+  "build": {
+    "builder": "NIXPACKS",
+    "buildCommand": "pip install -e .[asgi]"
+  },
+  "deploy": {
+    "startCommand": "uvicorn asgi_app:app --host 0.0.0.0 --port $PORT",
+    "healthcheckPath": "/health",
+    "healthcheckTimeout": 30,
+    "restartPolicyType": "ON_FAILURE",
+    "restartPolicyMaxRetries": 3
+  },
+  "variables": {
+    "ALLOWED_ORIGINS": "*",
+    "LOG_LEVEL": "info"
+  }
+}