Add subclass/specialization support

[avandenberghe]

Summary

Classes in many games have specializations (subclasses) that determine how a class fulfills a role. For example, a WoW Mage has three specs: Arcane, Fire, and Frost — all DPS. A Druid can be Balance (DPS), Feral (DPS/Tank), Restoration (Healer), or Guardian (Tank).

Currently bbGuild has classes and roles but no layer between them. This means we can't express "this player plays a Frost Mage" — only "this player is a Mage" and separately "this player's role is DPS".

Proposed design

New bb_specializations table:

Column	Type	Description
spec_id	INT (PK, auto)	Primary key
game_id	VARCHAR	Game identifier
class_id	INT	FK to bb_classes
role_id	INT	FK to bb_gameroles
spec_name	VARCHAR	Display name (via bb_language)
spec_icon	VARCHAR	Icon filename

Design questions to resolve

1. Is a spec always tied to exactly one role? In WoW, yes — each spec has a fixed role. Other games may differ.
2. Can a class have zero subclasses? Custom game or simpler games shouldn't require them. The feature should be optional per game.
3. Should the player model track current spec? Add player_spec_id to bb_players (nullable).
4. Should recruitment specify spec or just class+role? Currently recruitment is class+role. Spec-level recruitment would be more precise.
5. How do game plugins seed specs? WoW plugin would provide all specs; Custom game would have none. The installer pattern already supports this.

Scope of changes

• New migration: bb_specializations table + bb_language entries + nullable player_spec_id on bb_players
• Model: new specialization class in model/games/rpg/
• ACP: manage specs per class on the Edit Game page (nested under classes)
• Game plugins: WoW plugin seeds all specs; other plugins opt-in
• Roster: optionally display spec alongside class
• Recruitment: optionally recruit by spec
• Player edit (ACP/UCP): spec dropdown filtered by selected class

Phase

Phase 2 feature. Not blocking any current functionality.

Terminology

Different games use different terms:

• WoW: Specialization (spec)
• FFXIV: Job (with base class)
• GW2: Elite Specialization / Trait Line
• Generic: Subclass

The UI label should come from the game plugin (default: "Specialization").