Deprecate legacy Login/Register, add admin events, members, webhooks

- Mark Register() and Login() as Deprecated (use Better Auth directly)
- Add admin_events.go, members.go, webhooks.go to match backend API
- Sync types with backend changes

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

webhooks.go

@@ -0,0 +1,29 @@
+package elydora
+
+import (
+	"fmt"
+	"net/http"
+)
+
+// ListWebhooks retrieves all registered webhooks for the organization.
+func (c *Client) ListWebhooks() (*ListWebhooksResponse, error) {
+	var result ListWebhooksResponse
+	if err := c.doGet("/v1/webhooks", &result); err != nil {
+		return nil, err
+	}
+	return &result, nil
+}
+
+// RegisterWebhook registers a new webhook endpoint for the organization.
+func (c *Client) RegisterWebhook(req *RegisterWebhookRequest) (*RegisterWebhookResponse, error) {
+	var result RegisterWebhookResponse
+	if err := c.doPost("/v1/webhooks", req, &result); err != nil {
+		return nil, err
+	}
+	return &result, nil
+}
+
+// DeleteWebhook deletes a registered webhook by ID.
+func (c *Client) DeleteWebhook(webhookID string) error {
+	return c.doRequest(http.MethodDelete, fmt.Sprintf("/v1/webhooks/%s", webhookID), nil, nil)
+}