render: paint video on the clicked wall face (no visible anchor block)

The anchor block becomes invisible and non-collidable; it exists only as a
BlockEntity host in the air block adjacent to the clicked wall. The renderer
now translates and rotates the textured quad so it sits flush against the
surface of the wall the user actually clicked, on any of the six faces.

Stick interaction:
  right-click face → place anchor at hit.relative(face), facing=face, open GUI
  right-click face with anchor already there → reopen the GUI
  sneak + left-click face with stick → delete the anchor on that face
The anchor's selection outline / collision / occlusion are all empty, so the
player can target the wall block behind it without interference.

JavaCV / streaming polish:
- Bump missing-JavaCV log to WARN so users notice when the runtime jar is
  not installed (previously buried at INFO).
- Add HTTP resilience options: `timeout`, `reconnect`, `reconnect_streamed`,
  `reconnect_at_eof`, and a `user_agent` so picky servers don't 403 us.

gradle.properties

@@ -5,7 +5,7 @@ org.gradle.configuration-cache=false
 
 # Mod
 mod_id=video_player
-mod_version=0.3.1
+mod_version=0.4.0
 maven_group=com.ejclaw.videoplayer
 archives_base_name=video_player