✨ Update to Minecraft 26.3

[cacaview]

Draft — ported to Minecraft 26.3 (both loaders). NeoForge ✅ runs; Fabric ⚠️ compiles but is
blocked by an upstream 26.3 toolchain crash. REI still pending.

Ports Controllable to Minecraft 26.3 for both NeoForge 26.3.0.3-beta and Fabric
0.161.0+26.3, following the existing per-version branch convention. Based on multiloader/26.2.

26.3 moved the client input layer from GLFW to SDL and renamed/removed several client APIs,
so this is more than a version bump.

Still needed before merge

• REI: re-enable once a 26.3 RoughlyEnoughItems build exists (see note below).
• Fabric runtime: compiles cleanly, but :fabric:runClient is currently blocked by an
  upstream Fabric/Mixin 26.3 crash (see Test results below) — re-test once a working
  Fabric 26.3 toolchain ships.

Changes

Input (GLFW → SDL / InputConstants)

• Removed the GLFW backend (client/input/glfw/*, InputLibrary.GLF) — 26.3 no longer ships
  org.lwjgl.glfw.
• Key/mouse constants now come from com.mojang.blaze3d.platform.InputConstants.
• MouseHandler.onMove mixin updated to the new 4-double signature (the 26.3 load-time crash).
• Fabric: FabricClientHelper drops the GLFW backend — key/mouse action constants are now plain
  ints (0=release, 1=press, 2=repeat) and KeyEvent.scancode() is gone, so it passes 0.

API renames

• Window.toggleFullScreen()/isFullscreen() → setFullscreen(boolean) + options.fullscreen().
• LivingEntity.drop(boolean) → drop(ItemStack, boolean, Prediction.PREDICTED).
• AbstractContainerScreen: getGuiLeft/getGuiTop/getXSize/getYSize/getSlotUnderMouse →
  getLeftPos/getTopPos/getImageWidth/getImageHeight/getHoveredSlot.
• JEI IngredientGrid/IngredientGridWithNavigation/IngredientListRenderer/
  IIngredientListOverlayContents moved to mezz.jei.gui.overlay.ingredients.*.
• neoforge.mods.toml: logoFile/logoBlur → iconFile.

Versions

• java_version 25 → 26; minecraft_version/neo_form_version 26.2 → 26.3.
• NeoForge: neoforge_version 26.2.0.3-beta → 26.3.0.3-beta; neoforge_version_range → [26.3,).
• Fabric: fabric_version 0.152.2+26.2 → 0.161.0+26.3; fabric_loader_version 0.19.3 → 0.19.5;
  fabric_minecraft_version_range ~26.2- → ~26.3-.
• JEI → 31.0.0.7 / 26.3.
• Build plugins: moddev 2.0.141 → 2.0.147, foojay-resolver-convention 0.10.0 → 1.0.0.

Fabric — no other code changes needed

• The Fabric mixins and access-widener field accesses (screen.topPos, leftPos, imageWidth,
  imageHeight, hoveredSlot) are unchanged: the 26.3 getter renames did not affect the widened
  field names.

⚠️ Breaking changes / notes

1. REI support is disabled — no 26.3 build of RoughlyEnoughItems exists yet, so the REI
   dependency, PointHelperMixin, and its mixins.json entry were removed. JEI still works.
   To re-enable once 26.3 REI ships: uncomment the REI lines in common/build.gradle and
   neoforge/build.gradle, restore PointHelperMixin.java + its mixins.json entry, and bump
   rei_version to the 26.3 build.
2. GLFW input option removed — InputLibrary now only has SDL2; any existing config with
   inputLibrary=GLFW must be set to SDL2.

Test results (26.3)

• NeoForge — ✅ launches & runs. :neoforge:jar builds cleanly; :neoforge:runClient boots on
  26.3: SDL window created (LWJGL 3.4.3, OpenGL backend), the mod initializes —
  Successfully updated 180 gamepad mappings — ResourceManager reloads mod/controllable,
  sound engine starts, main menu reached, no crash / no InvalidInjectionException.
  (In-game controller play also confirmed separately.)
• Fabric — ⚠️ compiles, runtime blocked upstream. :fabric:jar builds cleanly;
  :fabric:runClient crashes at launch on 26.3 in Fabric API's fabric-content-registries-v0
  (@ModifyExpressionValue on LivingEntity.aiStep → Mixin ClassInfo.findInterface NPE while
  computing common supertypes). Reproduces on both 0.160.7+26.3 and 0.161.0+26.3, so it's an
  upstream Fabric/Mixin 26.3 toolchain issue, not a Controllable code defect (Controllable's
  Fabric mixins don't touch LivingEntity or use @ModifyExpressionValue).

Intended to be merged as a new multiloader/26.3 branch ("Create a branch on merge") — not into multiloader/26.2.