v1.21.1-0.3.0

Added

• Combined natural regeneration (combineNaturalRegeneration, enabled by default, applies while
  hunger is not shared): the shared health heals at the rate of a single player, only while every
  player meets the vanilla regeneration conditions (fast regeneration needs everyone at full hunger
  with saturation), and each heal drains hunger from all players. Previously, each fed player's own
  regeneration was added to the shared health separately, so players in safety could out-heal the
  danger the rest of the group was in.
• A concise chat summary of how much damage each player took since the shared health was last full,
  shown when the shared life ends. Disable with announceDeathSummary.
• The shared life is now saved with the world: a restart resumes the shared health (and hunger and
  experience, while shared) where it left off, instead of re-seeding it from a player. Seeding now
  only starts a genuinely new life — a fresh world, or the respawn after a shared death.

Changed

• shareHunger now defaults to disabled, making everyone keeping their own hunger topped up (see
  combineNaturalRegeneration) the default experience. Existing config files keep their saved
  value.
• shareDeath now defaults to disabled. Death sharing still implicitly applies while shareHealth
  is enabled, so the default experience is unchanged; existing config files keep their saved value.

Fixed

• Fixed shareDeath doing nothing while shareHealth was disabled: one player's death now kills
  everyone even when only death sharing is enabled
• Fixed the death summary never being announced when a death ended the shared life. It arrives right
  after the death messages.
• Fixed switching out of creative or spectator mode not joining the player into the shared life:
  they now sync onto the live shared health — or re-seed it from their own state after a total
  death — the same way joining the server does.
• Fixed a new shared life inheriting the previous life's residual exhaustion and hidden
  regeneration timer: the shared food state now starts fresh, seeded only from the re-seeding
  player's food level and saturation.