test(project-files): read the realtime proof's new file through its content route

The dead-code cleanup removed the Project file metadata GET, so the realtime suite's
readability check got a 405. The reader now fetches the file's bytes from
/api/projects/[id]/files/[fileId]/content, the source URL the product's file view
reads, and checks the created content.

Author: waleedlatif1

apps/sim/scripts/test-file-list-realtime-e2e.ts

@@ -347,11 +347,14 @@ try {
             revision = required(json(await request(`${prefix()}/${fileId}/versions`)).revision)
           })
       )
-      assert.equal(
-        toRecord(json(await request(`${prefix()}/${fileId}`, 'GET', undefined, readerCookie)).file)
-          .id,
-        fileId
+      const readable = await request(
+        `${prefix()}/${fileId}/content`,
+        'GET',
+        undefined,
+        readerCookie
       )
+      assert.equal(readable.status, 200, 'Unexpected HTTP status; inspect private app logs')
+      assert.equal(readable.text, 'first version')
       assert.equal(retainedMembership.projectId, fixture.projectId)
       assert.equal(workspaceEvents.length, 0)
     }