fix(rest): fix type test errors for content+schema guard and missing expect

- Make arrayBuffer and stream @ts-expect-error tests single-line so the
  directive covers the entire statement (multi-line caused the error to
  land on individual properties, making the directive appear unused)
- Replace runtime expect() with satisfies check in type-only test file
  (expect is not available in the typescript-tests tsconfig)

Co-authored-by: Nathaniel Tucker <me@ntucker.me>

Author: cursoragent

packages/rest/typescript-tests/types.test.ts

@@ -2054,18 +2054,10 @@ it('content property: schema constraint', () => {
   new RestEndpoint({ path: '/x' as const, content: 'text', schema: Article });
 
   // @ts-expect-error - schema incompatible with content: 'arrayBuffer'
-  new RestEndpoint({
-    path: '/x' as const,
-    content: 'arrayBuffer',
-    schema: Article,
-  });
+  new RestEndpoint({ path: '/x' as const, content: 'arrayBuffer', schema: Article });
 
   // @ts-expect-error - schema incompatible with content: 'stream'
-  new RestEndpoint({
-    path: '/x' as const,
-    content: 'stream',
-    schema: Article,
-  });
+  new RestEndpoint({ path: '/x' as const, content: 'stream', schema: Article });
 
   // content: 'json' allows schema
   new RestEndpoint({
@@ -2153,5 +2145,11 @@ it('content property: extend and subclass', () => {
   const subclassed = new BlobEndpoint({
     path: '/files/:id' as const,
   });
-  expect(subclassed.content).toBe('blob');
+  subclassed.content satisfies
+    | 'blob'
+    | 'json'
+    | 'text'
+    | 'arrayBuffer'
+    | 'stream'
+    | undefined;
 });