flask-smorest with subdomains and redoc

I have this sample app

```py
from flask import Flask, jsonify
from flask_smorest import Api, Blueprint as SmorestBlueprint

# Initialize Flask app
app = Flask(__name__, subdomain_matching=True)
app.url_map.default_subdomain = "docs"
app.config["API_TITLE"] = "My API"
app.config["API_VERSION"] = "v1"
app.config["OPENAPI_VERSION"] = "3.0.2"
app.config["OPENAPI_URL_PREFIX"] = "/"
app.config["OPENAPI_REDOC_PATH"] = "/redoc"
app.config[
"OPENAPI_REDOC_URL"
] = "https://cdn.jsdelivr.net/npm/redoc/bundles/redoc.standalone.js"
app.config[
"SERVER_NAME"
] = "example.com:5000" # Configure the server name to handle subdomains

# Initialize API
api = Api(app)

# Create 'account' and 'manage' blueprint
account_blp = SmorestBlueprint("account", "account")
manage_blp = SmorestBlueprint("manage", "manage")

@account_blp.route("/info", subdomain="account")
def account_info():
return jsonify({"message": "Account Info"})

@manage_blp.route("/settings", subdomain="manage")
def manage_settings():
return jsonify({"message": "Manage Settings"})

# Set up Redoc for each subdomain
redoc_html = """

Redoc





body {
margin: 0;
padding: 0;
}

"""

# Register blueprints with API
api.register_blueprint(account_blp, subdomain="account")
api.register_blueprint(manage_blp, subdomain="manage")

# print routes to see whats registered
for rule in app.url_map.iter_rules():
methods = ",".join(rule.methods)
print(f"{rule.endpoint:25s} {methods:20s} {rule.rule}")

if __name__ == "__main__":
# Run the app on all interfaces to accept requests from subdomains
app.run(debug=True, host="0.0.0.0", port=5000)

```

I added the entry below in `/etc/hosts`

```
127.0.0.1 account.example.com
127.0.0.1 manage.example.com
127.0.0.1 docs.example.com
```

- `http://account.example.com:5000/info` works
- `http://manage.example.com:5000/settings` works

`http://docs.example.com:5000/redoc` works but server URL for each endpoint is missing. Both endpoints starts with `http://docs.example.com:5000`

Reproduce the sample application with Flask subdomain matching, the API configuration, and the account and manage blueprint registrations. Inspect the generated OpenAPI document and Redoc endpoint behavior; done means the documented endpoint server URLs preserve the appropriate subdomains instead of using docs.example.com for both.

Written by the indexing model from the issue text.