Torchlight

Six fixes, backed by a new runtime test suite (59 assertions on Paper 1.21.11 and 26.2):

• Hand-placed light blocks are never modified or removed any more.
• Two players on the same block: the light no longer goes out when one of them leaves; the brighter source wins.
• No stale light left behind when a player has no free block around them.
• Light under water (there was none) - water is restored when you move on, no air pockets. Flowing water is left alone.
• The jar reports its real version in /plugins. No config changes needed.