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.