Replace safetensors with APR format

- Delete demo_model.safetensors (65KB stub)
- Delete model.safetensors (redundant after APR conversion)
- Add model.apr (6.7GB - APR format with metadata wrapper)
- Add *.apr to LFS tracking

The APR format provides:
- Embedded model card metadata
- Architecture information
- Validation checksums

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitattributes

@@ -33,3 +33,4 @@ saved_model/**/* filter=lfs diff=lfs merge=lfs -text
 *.zip filter=lfs diff=lfs merge=lfs -text
 *.zst filter=lfs diff=lfs merge=lfs -text
 *tfevents* filter=lfs diff=lfs merge=lfs -text
+*.apr filter=lfs diff=lfs merge=lfs -text

demo_model.safetensors → model.apr

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:37e51ae9da4294bbea18431148c58441f11b5f52e6d371c1f506293e8beb8aef
-size 65856
+oid sha256:71a74e5addd015d83a8c605aec03ad7aed1932d59350a5c1aa5915bba2d16ba1
+size 7108146756

model.safetensors

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:746e0ea4b7811bb101d4a2a790972e7a1eee721df36c37314215eebe60db7421
-size 6174656768