Implement SMSG_SPELLDAMAGESHIELD, SMSG_SPELLORDAMAGE_IMMUNE; route MSG_MOVE in SMSG_MULTIPLE_MOVES

- SMSG_SPELLDAMAGESHIELD: parse victim/caster/damage fields and show SPELL_DAMAGE
  combat text for player-relevant events (damage shields like Thorns)
- SMSG_SPELLORDAMAGE_IMMUNE: parse packed caster/victim guids and show new
  IMMUNE combat text type when player is involved in an immunity event
- Add CombatTextEntry::IMMUNE type to spell_defines.hpp and render it as
  white "Immune!" in the combat text overlay
- handleCompressedMoves: add MSG_MOVE_* routing so SMSG_MULTIPLE_MOVES
  sub-packets (player movement batches) are dispatched to handleOtherPlayerMovement
  instead of logged as unhandled; fix runtime-opcode lookup (non-static array)

include/game/spell_defines.hpp

@@ -51,7 +51,7 @@ struct CombatTextEntry {
     enum Type : uint8_t {
         MELEE_DAMAGE, SPELL_DAMAGE, HEAL, MISS, DODGE, PARRY, BLOCK,
         CRIT_DAMAGE, CRIT_HEAL, PERIODIC_DAMAGE, PERIODIC_HEAL, ENVIRONMENTAL,
-        ENERGIZE, XP_GAIN
+        ENERGIZE, XP_GAIN, IMMUNE
     };
     Type type;
     int32_t amount = 0;