Add desktop binary export support to the examples

win-x86, win-x64, linux-x64 and mac-universal targets, validated on
the pong pipeline: Makefile binaries/ci-binaries targets, desktop
export presets, ci-binaries step in the Woodpecker example. Mac is a
single universal (intel + arm) build with built-in ad-hoc codesign and
needs ETC2 ASTC texture import enabled in project.godot.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

example-woodpecker.yaml

@@ -9,6 +9,7 @@ steps:
     image: git.teletypegames.org/internal/godot-builder:4.6
     commands:
       - make ci-export
+      - make ci-binaries
 
   - name: artifact
     image: alpine