test(integration): clean up background-removal test-harness leftovers (#281)

backgroundRemoval.integration.test.ts exported seedSubmission for no reason — nothing imports it, since draftingBackgroundRemoval.integration.test.ts and adminItemDrafts.integration.test.ts each wrote their own seeding helpers. Dropped the export, kept the function for local use.

All three of these suites create a temporary uploads directory with mkdtemp and point UPLOADS_DIR at it, but none of them removed the directory afterward or restored the previous UPLOADS_DIR value — checked and the leak existed in all three, not just the one the review flagged. Each afterEach now removes its temp directory with fs.rm and restores (or deletes) UPLOADS_DIR to what it held before the test touched it, so this suite no longer leaves rubbish in the OS temp directory or a stale environment variable for whatever runs after it in the same process.

This is test scaffolding cleanup, not a feature change — no runtime path in the application deletes anything.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/tests/integration/adminItemDrafts.integration.test.ts

@@ -317,10 +317,12 @@ describe('the review queue’s background-removal control', () => {
 
   let uploads = '';
   let stub: http.Server | null = null;
+  let previousUploadsDir: string | undefined;
 
   /** A stub sidecar on an ephemeral port, and a temporary uploads directory. */
   async function startStub(status: number, body: Buffer | string): Promise<void> {
     uploads = await fsp.mkdtemp(path.join(os.tmpdir(), 'adminbg-'));
+    previousUploadsDir = process.env.UPLOADS_DIR;
     process.env.UPLOADS_DIR = uploads;
 
     stub = http.createServer((req, res) => {
@@ -340,6 +342,13 @@ describe('the review queue’s background-removal control', () => {
       await new Promise<void>((resolve) => stub!.close(() => resolve()));
       stub = null;
     }
+    if (uploads !== '') {
+      await fsp.rm(uploads, { recursive: true, force: true });
+      uploads = '';
+    }
+    if (previousUploadsDir === undefined) delete process.env.UPLOADS_DIR;
+    else process.env.UPLOADS_DIR = previousUploadsDir;
+    previousUploadsDir = undefined;
   });
 
   /** A ready draft with one photo, on disk, named to match the assertions. */