Moonlight Magic

Balance update: learning economy + compendium / wheel fixes (no protocol change).

Learning economy:
- Intermediate spells 20 -> 8, advanced 100 -> 20, Magic Halo 30 -> 15; novice stays 3.
- Each spell still teaches at most 10 points: intermediate is +2 net, advanced -10 net,
  funded by the lower tiers. The full spell list costs 240 against 280 total income,
  so "only one advanced spell" is gone.

Compendium:
- Survival no longer auto-refills the book every tick (creative keeps the lost-book fallback).
- Summoning now checks the inventory, ender chest, chests, the ground and item frames first;
  if the book is nearby it says so instead of spawning a second one.
- Right-clicking the floating book now picks it up instead of casting the summon again;
  the book spawns at a fixed horizontal offset, so looking down no longer drops it into
  your inventory.

Spell wheel:
- Six is the page size, not a cap. With a single page the footer reads
  "N spells learned - 6 per page"; with more pages it still reads "Page x/y - scroll to flip".