Healt Alert Tweaks

Healt Alert Tweaks - 1.21.9 - 1.21.10

Merged compatibility build for Minecraft 1.21.9 and 1.21.10.

Changed

• Added support for Minecraft 1.21.9.
• Added support for Minecraft 1.21.10.
• Merged both versions into one compatibility build.
• Updated dependency targets for the 1.21.9/1.21.10 line.

Technical

• Verified the same vignette rendering methods are compatible across both versions.
• Verified the same GUI configuration code path works across both versions.
• Verified the same heartbeat sound playback logic works across both versions.
• No feature behavior changes from the previous compatibility line.