Death Cache and Memorial System

Add a new death system that improves item recovery in Survival and creates meaningful memories in Hardcore. When a player dies, a Death Cache appears at the death location and stores their items safely. The player can return using the Recovery Compass, which points directly to the cache. Features: - Items are protected from fire, lava, explosions, and despawning. - The cache disappears after the player retrieves their items. - Death still has a penalty by removing some experience, keeping survival challenging. - In water, the cache floats or stays accessible. - If it appears in lava, it teleports to the nearest safe location. - If it appears inside blocks, it moves to the nearest open space. In Hardcore mode, the Death Cache becomes a permanent Memorial Grave instead: - Shows the player's name. - Displays how many days they survived. - Shows days since the death. - Becomes a landmark that players can revisit to remember fallen friends or important moments. Minecraft is a game about exploration and creating stories. Death should have consequences, but losing hours of progress because items disappear before returning can feel frustrating rather than challenging. This system would preserve the danger of survival while making deaths more meaningful and memorable.