Drop dead Git LFS assets with never-uploaded objects

Remove 158 LFS-tracked files whose objects never reached origin
(incomplete push) and so couldn't be fetched on a fresh checkout:
Rukhanka Samples~/ demo assets (Unity-ignored), editor inspector
icons + RukhankaAnimation.pdf, and 2 doc screenshots. All editor-only
or Unity-ignored; verified non-essential (clean compile, 390/390 tests,
clean netcode boot without them). Each asset removed with its .meta.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Packages/com.rukhanka.animation/Samples~/Samples/SampleAssets/Armature/Models/Armature.fbx

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:855e05c72da761ccd2bfb2ec8e77599677d327d627ee51c0bf6a818ce958b7f1
-size 5021936

Packages/com.rukhanka.animation/Samples~/Samples/SampleAssets/Armature/Models/Armature_Humanoid.fbx

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:855e05c72da761ccd2bfb2ec8e77599677d327d627ee51c0bf6a818ce958b7f1
-size 5021936