v0.3.0 step 4: type map + particle_type.target = "onehot"/"embedding"

Builds the shared top-N-plus-other PDG/material maps (pooling both primary
and secondary occurrences for PDG, directly targeting the meeting's
species-collapse failure mode) and wires up conditioning.{particle,material}
= "onehot" plus stage2_model.particle_type.target in ("onehot", "embedding")
end-to-end: setup-cache persistence, Stage2OneShot's type_head (flow/ddpm)
vs. folded+ST-Gumbel-relaxed adversarial slice (wgan), and the corresponding
CE/MSE training losses. particle_type.target = "physical" stays byte-for-byte
unchanged, keeping the v0.2 migration shim's bit-identical guarantee intact.
giant predict/rollout fail loudly on a onehot/embedding checkpoint until
full decode support lands in step 6.

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

tests/test_transforms.py

@@ -319,7 +319,7 @@ def test_build_features_clamps_n_sec_label_to_k_max():
     pdg_map = {11: 0}
     mat_map = {"PbWO4": 0}
 
-    _, _, _, n_sec, _, _, _, _ = build_features(data, pdg_map, mat_map)
+    _, _, _, n_sec, _, _, _, _, _ = build_features(data, pdg_map, mat_map)
 
     assert n_sec.max() <= K_MAX
     np.testing.assert_array_equal(n_sec, [0, 5, K_MAX])
@@ -361,7 +361,7 @@ def test_build_features_proc_idx_zero_without_proc_map():
     )
     pdg_map, mat_map = {11: 0}, {"PbWO4": 0}
 
-    *_, proc_idx, _, _ = build_features(data, pdg_map, mat_map)
+    *_, proc_idx, _, _, _ = build_features(data, pdg_map, mat_map)
 
     np.testing.assert_array_equal(proc_idx, [0, 0, 0])
 
@@ -373,7 +373,7 @@ def test_build_features_proc_idx_looks_up_proc_map():
     pdg_map, mat_map = {11: 0}, {"PbWO4": 0}
     proc_map = {"compt": 0, "phot": 1, "eIoni": 2}
 
-    *_, proc_idx, _, _ = build_features(data, pdg_map, mat_map, proc_map=proc_map)
+    *_, proc_idx, _, _, _ = build_features(data, pdg_map, mat_map, proc_map=proc_map)
 
     np.testing.assert_array_equal(proc_idx, [0, 1, 2])