Inconsistent class icon sizes and missing lotro_unknown.png

[avandenberghe]

Icon size inconsistencies

Class icons have mixed dimensions instead of a uniform size:

Size	Icons
20x20	lotro_beorning.png
38x38	lotro_warden.png
43x43	burglar, captain, champion, guardian, hunter, lore-master, minstrel, rune-keeper
48x48	blackarrow, defiler, reaver, stalker, warleader, weaver

All icons should be normalized to a consistent size (suggest 48x48 to match the largest existing ones).

Missing icon

• lotro_unknown.png — referenced by class_id 0 but file does not exist

[avandenberghe]

Extending scope: #7 just added 3 new classes/races with no icon assets yet — lotro_brawler/lotro_mariner (class icons) and lotro_hobbit_river (race icon). Same bucket of work as this issue's existing icon-consistency scope, flagging here rather than opening a new ticket.