Skyveil Cloudlands Pass 8

- Rain clouds now behave more like they already hold water:
  - player-placed/generated rain_cloud and charged_rain_cloud blocks schedule passive drip ticks
  - cauldrons directly below clear air under the cloud can refill without needing dripstone or active weather
  - random ticks still provide additional drip attempts
  - visible water drip particles are more frequent under rain-cloud blocks

- Added high-sky heavenly haze:
  - while players are high in the Cloudlands and near Skyveil cloud blocks, the server sends sparse white cloud particles around them
  - this approximates a soft foggy sky-biome feel without using heavy renderer fog hooks
  - conservative defaults keep visibility ahead readable and reduce rendering cost

- New config keys:
  - rain_clouds_passive_drip_ticks
  - rain_clouds_visible_drip_chance
  - enable_cloudlands_heavenly_haze
  - cloudlands_heavenly_haze_min_y
  - cloudlands_heavenly_haze_requires_near_cloud
  - cloudlands_heavenly_haze_scan_radius
  - cloudlands_heavenly_haze_interval_ticks
  - cloudlands_heavenly_haze_particle_count
  - cloudlands_heavenly_haze_spread
