fix(ml): align tagger + downloader with Camie v2 actual layout (model.onnx -> camie-tagger-v2.onnx + JSON metadata + ImageNet preprocessing + sigmoid on refined output)

The HF repo Camais03/camie-tagger-v2 has camie-tagger-v2.onnx (789 MB)
+ camie-tagger-v2-metadata.json (7.77 MB) at root, NOT model.onnx +
selected_tags.csv. Tags ship as nested JSON (dataset_info.tag_mapping)
not CSV. Per the published onnx_inference.py reference: input is NCHW
not NHWC, normalize with ImageNet mean/std, pad-square color (124,116,
104), sigmoid the second output (refined predictions) not the first.

Operator hit this during the IR migration ML backfill — download_models
silently fetched only 3 json files (allow_patterns matched nothing
useful), tagger.load() then raised RuntimeError. Fetched the actual
v2 layout via WebFetch, rewrote tagger to match published reference.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_ml_tagger.py

@@ -40,5 +40,8 @@ def test_get_tagger_singleton():
 
 def test_load_raises_when_model_missing(tmp_path):
     t = Tagger(model_dir=tmp_path / "nonexistent")
-    with pytest.raises(RuntimeError, match="model.onnx missing"):
+    # Match the trailing "missing at <path>" rather than the specific
+    # filename, so a future model-version bump (camie-tagger-v3.onnx, etc.)
+    # doesn't bounce this test.
+    with pytest.raises(RuntimeError, match=r"\.onnx missing at "):
         t.load()