System Music Notification Toast

Added

• Minecraft 26.2 support
• Playerctl availability check on Linux with alert toast
• Flatpak D-Bus permission detection with alert toast
• Warning triangle icon for alert toasts (vs music note for normal toasts)
• recheckAvailability() — periodic 60-second background recheck on daemon thread detects if playerctl was installed mid-game

Changed

• Migrated from Yarn mappings to Mojang official mappings (26.1+ requirement)
• Build toolchain: Loom 1.17, Gradle 9.5.1, Fabric Loader 0.19.3, Java 25
• Toast manager access: getToastManager() → gui.toastManager() (26.2 Gui reorganization)
• Toast rendering: draw() → extractRenderState(), GuiGraphicsExtractor API

Fixed

• Toast stops working after logout/rejoin (isShowing flag stuck true)
• Keybind shows "No music playing" instead of alert when playerctl missing