fix: track model files via Git LFS, not gitignore

.gitignore was blocking *.pkl and *.pt from git tracking entirely,
so git push sent a deletion commit to HuggingFace wiping the models.
.gitattributes already routes these through LFS correctly.
Removed the gitignore rules that were fighting LFS.

.gitignore

@@ -45,11 +45,7 @@ venv/
 # Reference data / trained models (too large for git -- use HuggingFace directly)
 data/reference/real/
 data/reference/ai/
-data/reference/*.pkl
-data/reference/*.pt
-data/reference/*.json
 data/reference/*.sha256
-data/reference/*.csv
 !data/reference/.gitkeep
 
 # Keep directory structure

data/reference/ensemble_xgb.pkl

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ade14f50c5869f07b422177f8d29953937ef489ceee1c25c5b20541f8eac60c6
+size 21308

data/reference/own_centroids.pkl

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a09d7bb9e755903451daa59e9266eb51372330eef1e4288f835a7c0c75fad122
+size 4426

data/reference/own_embedding_model.pt

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ac06cffb88fec51ac892c6c5e763b2af1ee2a7eeb83fc07640f195349f6b5867
+size 19220826