fix(extension): check a MakerWorld collection against the library in one call

The collection panel sent one /import/status request per model, all at
once. When any failed it counted the model as new, so a collection
already imported could offer to import almost everything again.

Add POST /import/status/batch and use it, falling back to paced
per-model checks on older instances. A failed check now shows an error
instead of guessing.

backend/src/routes/imports.ts

@@ -16,6 +16,7 @@ import {
   importPrintFromUrl,
   inspectImportLink,
 } from "../services/importService";
+import { findLibraryPrints } from "../services/collectionSyncService";
 import { resolveMakerworldCookie } from "../services/importResolvers";
 import {
   extractMakerworldBearerToken,
@@ -190,6 +191,21 @@ router.get(
   }),
 );
 
+const statusBatchSchema = z.object({
+  provider: z.enum(["makerworld", "thingiverse", "printables"]),
+  external_ids: z.array(z.string().max(64)).max(10_000),
+});
+
+// One query for a whole collection page; per-model /import/status calls bog down on big ones.
+router.post(
+  "/import/status/batch",
+  asyncHandler(async (req, res) => {
+    const body = parseBody(statusBatchSchema, req.body);
+    const prints = await findLibraryPrints(req.userId!, body.provider, body.external_ids);
+    res.json({ print_ids: Object.fromEntries(prints) });
+  }),
+);
+
 router.post(
   "/import/zip/entries",
   asyncHandler(async (req, res) => {

backend/tests/fillGaps.test.ts

@@ -227,6 +227,11 @@ describe("filling a model's missing details from its source", () => {
       .get(`/api/import/status?url=${encodeURIComponent(`https://makerworld.com/en/models/${designId}`)}`)
       .set(auth());
     expect(status.body.gaps).toEqual([]);
+    const batch = await request(app)
+      .post("/api/import/status/batch")
+      .set(auth())
+      .send({ provider: "makerworld", external_ids: [designId, "0"] });
+    expect(batch.body.print_ids).toEqual({ [designId]: print.id });
 
     // Clearing a field the source does have opens a gap again.
     await prisma.print.update({ where: { id: print.id }, data: { notes: null } });