Critical fixes

• Fixed infinite loop in fluid watch polling that burned the whole tick budget for 200 ticks on non-fluid blocks.
• Fixed music disc duplication at jukeboxes: state is now applied directly instead of going through AIR, so vanilla no longer drops a disc on every mirror update.
• Fixed busy-loop in the block queue when chunks were unloaded (8 ms per tick spent just shuffling keys).
• Fixed item drop avalanche: container contents are cleared before setBlockState, no more thousands of item entities per tick on large mirrors.
• Spawners are now actually forced to spawn.
• Removed the 847-position spawner scan on every mob load (~85k lookups/tick on dense chunks); positions are read from cached block entities instead.
• Fixed redstone poll starvation: a rotating cursor now guarantees the tail of the template gets polled.
• Fixed REDSTONE_LAST_STATE memory leak on block replacement.
• Fixed forced chunk tickets being taken inside the CHUNK_LOAD callback (chunk manager reentrancy).

Performance

• Mirror queue now stores only the latest state per position, so mirroring no longer degrades as the template grows
• Rewrote the queue as an O(1) structure, removed per-iteration allocations
• Fluid spread is throttled: max 48 fluid blocks per tick, radius 32, 2048 block cap. No more server freeze when you dump a water bucket
• Block updates are batched instead of sending one packet per block
• Block budget raised 6 → 10 ms, total budget 10 → 15 ms

Additions

• Persistence: template, signs, records and void worlds now survive a server restart
• /mirrormod on|off|status|clear — kill switch and diagnostics
• Void worlds: UUID-based ownership, permission-gated teleports, 5x5 spawn platform, 32x32 slot grid (max coord ~254k instead of 29.9M, so no more movement jitter or render glitches), plus /voidworld list
• Void dimension datapack (mirrormod:void) shipped with the mod
• Water buckets mirror correctly on the first pour (all candidate target positions are now checked)
• Template schema migration: contaminated templates from older builds are reset automatically, service platforms are permanently excluded from mirroring