Update to 26.3

[dekrom]

Merges mc-update (26.3-pre.1) into master and finishes the port for the 26.3 release.

Dependencies: Minecraft 26.3, Fabric Loader 0.19.5, Fabric API 0.162.0+26.3, Sodium mc26.3-0.9.2, Lithium mc26.3-0.26.2, Iris 1.11.7+26.3, ModMenu 21.0.0, ViaFabricPlus 5.1.1, Baritone 26.3-SNAPSHOT (MeteorDevelopment/baritone#17, so CI will not resolve it until that is published).

Merge: the conflicts were the keybind fixes on master (79a30a7, 56a7703, b587fb9) against the SDL input rework in mc-update. Master's modifier precedence and MacosUtil are kept (MacosUtil still exists in 26.3, under com.mojang.blaze3d.platform), the SDL mouse warp, KeyEvent.keycode(), Type.KEYBOARD and CursorType come from mc-update.

26.3 final vs pre.1

• Util.OS.openUri(String) is gone: Utils.openUri wraps Blaze3D.openUri + Util.parseAndValidateUntrustedUri.
• ViaFabricPlus 5 moved GeneralSettings behind the API; the mixin targets GeneralSettingsImpl and swaps the Orientation.RIGHT_TOP default for RIGHT_BOTTOM (same intent as the old 2 -> 4).
• ClientLevel.addBreakingBlockEffect was split into addBreakingBlockEffects (sound + particles) and a private addBreakingParticles; NoRender cancels the latter so the breaking sound is untouched.
• Super key is KEY_LGUI/KEY_RGUI, the Menu key goes through SDLScancode.SDL_SCANCODE_APPLICATION (no InputConstants constant for it), the ISO \| key through SDL_SCANCODE_NONUSBACKSLASH.

Input fixes on top of mc-update

• SDL reports left/right modifiers as separate bits and keeps NumLock/CapsLock state in every event, so the exact modifiers() == MOD_CONTROL checks in the GUI never matched a single Ctrl or anything with NumLock on. Input.modifiersMatch handles that; WidgetScreen, ModulesScreen and WTextBox use it.
• Keybind.Modifier drops CAPS_LOCK/NUM_LOCK (GLFW never reported them, SDL always does), otherwise modifier binds stop matching with NumLock on.
• KeyboardHud.isNativelyPressed compared a scancode against RELEASE; it now uses InputConstants.isKeyDown / Input.isButtonPressed.

Tested: ./gradlew build, dev client (mixin audit) clean, joined a singleplayer world with Baritone 26.3 installed, no mixin errors.