fix: make types compile under TypeScript 7.0

Both `@sendgrid/client` and `@sendgrid/mail` ship .d.ts files that
mix `export = instance` with `export {Class}` and silence the
diagnostic with `// @ts-ignore`. Pre-7.0, downstream consumers paid
no cost for this since named imports of the class still resolved.
TS 7.0 (the Go-port `tsgo` beta) tightens the rule and surfaces
TS2616 in every consumer that imports `Client` or `MailService`:

    error TS2616: 'Client' can only be imported by using
    'import Client = require("@sendgrid/client")' or a default import.

The fix mirrors the runtime: `module.exports = new Client();
module.exports.Client = Client;`. Modeling that as a `Client`
instance with a `Client: typeof Client` instance member lets TS
expose the class through `client.Client` AND through the named
import `import { Client } from "@sendgrid/client"` without any
escape hatches. Same pattern for MailService. Existing TS test
fixtures (incl. `new Client()` and `setClient(client: Client)`)
keep passing under both tsc 5.9 and tsgo 7.0 unchanged.

Also bring tsconfig.json up to TS 7.0 minimums so the test fixtures
type-check under tsgo: drop the removed `baseUrl`, add the now-
required leading `./` to path mappings, and declare `types: ["node"]`
explicitly (auto-load of all @types is gone in 7.0).

Verified with tsc@5.9.3 and @typescript/native-preview@7.0.0-dev.

Author: FelipeLahti

packages/client/src/client.d.ts

@@ -5,6 +5,13 @@ import {ClientResponse} from "@sendgrid/client/src/response";
 declare class Client {
   constructor();
 
+  /**
+   * Class itself, attached at runtime via `module.exports.Client = Client`.
+   * Lets `import client = require("@sendgrid/client")` consumers reach the
+   * class via `client.Client`.
+   */
+  Client: typeof Client;
+
   /**
    * Set the SendGrid API key.
    */
@@ -52,7 +59,4 @@ declare class Client {
 }
 
 declare const client: Client;
-// @ts-ignore
-export = client
-
-export {Client};
+export = client;

packages/mail/src/mail.d.ts

@@ -1,9 +1,16 @@
-import {Client} from "@sendgrid/client";
+import sgClient = require("@sendgrid/client");
 import {ClientResponse} from "@sendgrid/client/src/response";
 import {ResponseError} from "@sendgrid/helpers/classes";
 import {MailDataRequired} from "@sendgrid/helpers/classes/mail";
 
+type Client = InstanceType<typeof sgClient.Client>;
+
 declare class MailService {
+  /**
+   * Class itself, attached at runtime via `module.exports.MailService = MailService`.
+   */
+  MailService: typeof MailService;
+
   /**
    * SendGrid API key passthrough for convenience.
    */
@@ -41,10 +48,4 @@ declare class MailService {
 }
 
 declare const mail: MailService;
-// @ts-ignore
 export = mail;
-
-export {MailService};
-export {MailDataRequired};
-export {ClientResponse};
-export {ResponseError};

tsconfig.json

@@ -3,9 +3,9 @@
         "noEmit": true,
         "module": "commonjs",
         "target": "es6",
-        "baseUrl": ".",
+        "types": ["node"],
         "paths": {
-            "@sendgrid/*": ["packages/*"]
+            "@sendgrid/*": ["./packages/*"]
         }
     },
     "include": [