test: update pre-existing stale specs for 2.0 multimodal + validation behavior

Fixes a backlog of integration/unit specs that asserted pre-2.0 behavior and
were failing CI (not caused by recent feature work):
- modality-aware empty-input error is 'No file(s) provided', not /no image/i
  (rotate, border, crop, resize, smart-crop, edge-cases, adversarial-extended,
  api, tool-factory-route)
- input validation rejects pre-enqueue with a clean 400 in 'error' (was a worker
  422 in 'details'): create-zip, extract-zip, merge-csvs
- resolveToolPool defaults unknown tools to the system pool (pool-routing)
- /upload and fetch-urls accept non-image content, validated per-tool at process
  time (api, fetch-urls)
- color-adjust legacy aliases were consolidated into adjust-colors: drop the
  removed-alias tests; retarget the format-preservation tests
- xml-to-csv gracefully converts a single non-repeating record to a 1-row CSV
- dropzone is multimodal; image-only filtering is opt-in via fileFilter
- factory-multi-input: register the synthetic test tools in the catalog so they
  route correctly (file modality for concat; image for the validation-prefix test)

Verified locally: unit 4546 passed, integration 8332 passed, typecheck + lint green.

tests/integration/adversarial-extended.test.ts

@@ -620,7 +620,7 @@ describe("Batch edge cases — extended", () => {
 
     expect(res.statusCode).toBe(400);
     const json = JSON.parse(res.body);
-    expect(json.error).toMatch(/no image/i);
+    expect(json.error).toMatch(/no file/i);
   });
 
   it("handles batch with duplicate filenames", async () => {
@@ -729,7 +729,7 @@ describe("Batch edge cases — extended", () => {
     // The zero-byte file is skipped, resulting in 0 valid files
     expect(res.statusCode).toBe(400);
     const json = JSON.parse(res.body);
-    expect(json.error).toMatch(/no image/i);
+    expect(json.error).toMatch(/no file/i);
   });
 });
 
@@ -1282,7 +1282,7 @@ describe("Batch with only zero-byte files", () => {
     // Zero-byte files are skipped during parsing, so 0 valid files
     expect(res.statusCode).toBe(400);
     const json = JSON.parse(res.body);
-    expect(json.error).toMatch(/no image/i);
+    expect(json.error).toMatch(/no file/i);
   });
 });