feature request: add Twilio host configuration for Ireland (IE1) SMS support

Problem

A customer is building self-serve onboarding for Italian restaurant owners with phone verification. Their legal team requires SMS OTP traffic to stay in the EU, and they want to use Twilio's Ireland (IE1) region from Logto Cloud.

The Twilio SMS connector currently hard-codes requests to:

https://api.twilio.com/2010-04-01/Accounts/{accountSID}/Messages.json

Users cannot configure an alternative Twilio API hostname through the connector configuration. The configuration schema and Console form also have no host field.

Twilio supports Programmable Messaging SMS in IE1 at api.dublin.ie1.twilio.com, using the same Messages API path. Its Messaging API documentation supports region-specific Auth Tokens or API keys. The existing connector's accountSID / authToken authentication should be verified with the IE1 Auth Token.

Because Logto Cloud users cannot patch the built-in connector, the hard-coded host prevents them from selecting IE1 through configuration.

Verified against master at bf1636c424c8621a42b8044432a9c9acfb9ae914: endpoint and form metadata, configuration schema.

Requested change

Add an optional host configuration field to @logto/connector-twilio-sms, exposed in both the connector configuration schema and Console form.

• Default to api.twilio.com when omitted, preserving existing configurations.
• Use the configured hostname to construct the HTTPS Messages API URL, retaining the existing API version and account-specific path.
• Define and validate the accepted hostname format; document that host is a hostname rather than a full API URL.
• Support host: "api.dublin.ie1.twilio.com" with the existing accountSID, an IE1-specific authToken, and an IE1 Messaging Service SID. Keep requests on the configured host; do not silently fall back to the US endpoint.
• Document the default and the IE1 setup, including region-specific credentials, Messaging Services, and compatible senders. Twilio documents that Messaging Services are region-isolated and only the Dublin edge is supported for Messaging in IE1. See the IE1 Messaging guide.
• Verify compatibility of the connector's existing request parameters with IE1, including its RiskCheck setting: Twilio lists SMS Pumping Protection as unsupported in IE1 in its feature availability documentation.
• Add tests for the default host, the IE1 host, and invalid input, including use of the supplied configuration when testing a connector before saving it. Validate the IE1 send flow with suitable regional credentials before claiming end-to-end support.

Keep this change focused on host configuration; no separate region/edge configuration model is required.

Data residency boundary

This feature enables selecting Twilio IE1; it should not promise that all end-to-end SMS traffic stays in the EU. Twilio's SMS EU data residency documentation scopes its processing/storage guarantee to the point of handoff to telecommunications providers, which may process data outside the EU. The customer's broader requirement also needs to account for their Logto/application deployment and telecom delivery.