fix(render): anchor video to clicked block's bottom-left, EAST/WEST flush

Three fixes for v0.4.1:

1. Video stick item rendered as missing-texture because 26.1.2 requires the
   new client_item descriptor at assets/<mod>/items/<name>.json. Add it; the
   existing models/item/video_stick.json is kept as the underlying model.

2. Quad placement now anchors the local (0,0) corner at the bottom-left of
   the wall face the player clicked, so the clicked block is the BL and the
   video grows up & right. Previously it was centered on the anchor.

3. EAST/WEST face rotations were swapped, which placed the quad on the far
   side of the air block (~1 block away from the wall) instead of flush.
   Derived the correct rotations from first principles:
     EAST = Axis.YP +90°  (local +Z → world +X, +X → -Z = north)
     WEST = Axis.YP -90°  (local +Z → world -X, +X → +Z = south)
   NORTH/SOUTH/UP/DOWN math re-verified — those were already correct.

gradle.properties

@@ -5,7 +5,7 @@ org.gradle.configuration-cache=false
 
 # Mod
 mod_id=video_player
-mod_version=0.4.0
+mod_version=0.4.1
 maven_group=com.ejclaw.videoplayer
 archives_base_name=video_player