Build for Minecraft 26.3

Adds 26.3 as a Stonecutter version, the last step of #39.

Input: 26.3 replaces GLFW with SDL, which numbers keys (scancodes),
modifiers and mouse buttons differently. Saturn keeps GLFW's numbers,
which common uses and the config's keybinds store, so saved keybinds
stay valid. The new Keys class converts at the boundary: key events,
modifiers and mouse buttons coming into Saturn's screens, and key codes
going to InputConstants. Its table pairs GLFW's codes with 26.3's
InputConstants of the same name. Key names come from the game on 26.3,
and version-specific code uses InputConstants' key constants rather
than GLFW's.

Rendering: Blaze3D's API moved to renderpearl, which Stonecutter
replacements cover. PoseStack's quaternion mulPose became rotate, and
TextureTarget takes a depth format instead of a flag. 26.3 compiles
shaders through SPIR-V and reorders the transforms block, so glass.fsh
takes explicit locations and the new order behind defines that
GlassRenderer sets, and the unlit cosmetics pipeline declares its
color target, which 26.3 requires.

OptionsScreen no longer takes whether a world is open.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

versions/26.3/gradle.properties

@@ -0,0 +1,17 @@
+# Done to increase the memory available to gradle.
+org.gradle.jvmargs=-Xmx1G
+org.gradle.parallel=true
+
+# IntelliJ IDEA is not yet fully compatible with configuration cache, see: https://github.com/FabricMC/fabric-loom/issues/1349
+org.gradle.configuration-cache=false
+
+# Fabric Properties
+# check these on https://fabricmc.net/develop
+minecraft_version=26.3
+loader_version=0.19.5
+
+fabric_api_version=0.161.0+26.3
+
+# Mod Properties
+maven_group=org.saturnclient
+archives_base_name=saturn-client