feat: discipline UI improvements - stat labels, prerequisites, mana type tab

- Add player-friendly label field to statBonus in DisciplineDefinition
- Show prerequisite requirements on locked discipline cards
- Disable activate button for locked disciplines
- Restructure elemental attunement into dedicated 'Mana Types' tab
- Add checkDisciplinePrerequisites utility function
- Update store to enforce prerequisite checking on activation
- Split discipline-prerequisites tests into separate file

src/lib/game/stores/discipline-slice.ts

@@ -8,9 +8,11 @@ import {
   calculateManaDrain,
   calculateStatBonus,
   canProceedDiscipline,
+  checkDisciplinePrerequisites,
   getUnlockedPerks,
 } from '../utils/discipline-math';
 import { baseDisciplines } from '../data/disciplines/base';
+import { elementalAttunementDisciplines } from '../data/disciplines/elemental';
 import { elementalRegenDisciplines } from '../data/disciplines/elemental-regen';
 import { elementalRegenAdvancedDisciplines } from '../data/disciplines/elemental-regen-advanced';
 import { enchanterDisciplines } from '../data/disciplines/enchanter';
@@ -23,6 +25,7 @@ import { MAX_CONCURRENT_DISCIPLINES } from '../types/disciplines';
 
 const ALL_DISCIPLINES = [
   ...baseDisciplines,
+  ...elementalAttunementDisciplines,
   ...elementalRegenDisciplines,
   ...elementalRegenAdvancedDisciplines,
   ...enchanterDisciplines,
@@ -86,6 +89,8 @@ export const useDisciplineStore = create<DisciplineStore>()(
           }).length;
           if (nonPaused >= s.concurrentLimit) return s;
           if (!canProceedDiscipline(def, existing, gameState)) return s;
+          const prereqCheck = checkDisciplinePrerequisites(def, s.disciplines, ALL_DISCIPLINES);
+          if (!prereqCheck.canProceed) return s;
 
           const discState = existing || { id, xp: 0, paused: false };
           return {