[Docs] Document DynamicMountDefinition for companion mounts

[Lyeeedar]

Summary

Documents the DynamicMountDefinition type introduced in commit e2f4064 (issue #9058) and adds the missing CompanionCharacterDefinition interface to the Character Structure doc.

Changes

docs/characters/companions.md

• Updated mount field in CompanionCharacterDefinition interface: mount?: MountItem → mount?: MountItem | DynamicMountDefinition
• Added new Dynamic Mounts section explaining first-match-wins condition evaluation, with a practical example showing realm-based and quest-based mount swaps
• Updated the Realm Definition Example to use DynamicMountDefinition instead of a static MountItem

docs/characters/character-structure.md

• Added Companion Definition subsection (previously absent — CompanionCharacterDefinition was referenced at line 132 but never defined)
• Includes the full CompanionCharacterDefinition interface with all interaction types and the mount field
• Added DynamicMountDefinition interface with documentation of the condition-evaluation semantics and first-match-wins resolution order

Game Changes Referenced

Commit	Description
e2f40648	Dynamic mounts for companions — new getCharacterMount utility, DynamicMountDefinition type, and `mount?: MountItem

Breaking Changes

None — DynamicMountDefinition is purely additive. Existing companion mount fields using a plain MountItem are unaffected.

🤖 Mod Documentation Updater — automated AI assistant