Donut RTP & RTP Zone

Added

• HeadDatabase ID support — GUI items can use a HeadDatabase head via material: "hdb-<id>" (requires HeadDatabase plugin). Existing material and head block formats are unchanged.
• Action bar cooldown sound — Optional sound played each second during the warmup countdown (actionbar-cooldown in config.yml). Disabled by default for backwards compatibility.
• Instant teleport option — Set instant-teleport: true to skip the warmup countdown and teleport immediately after a safe location is found.

Configuration

• New instant-teleport key in config.yml (default: false)
• New actionbar-cooldown section in config.yml (see inline comments for examples)
• HeadDatabase example under gui.items in config.yml
• Missing config keys are backfilled with sensible defaults on reload