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/__tests__/store-actions-discipline.test.ts

@@ -28,16 +28,16 @@ describe('DisciplineStore', () => {
 
     it('should not activate when concurrent limit reached', () => {
       useDisciplineStore.getState().activate('raw-mastery');
-      useDisciplineStore.getState().activate('elemental-attunement');
+      useDisciplineStore.getState().activate('attune-fire');
       expect(useDisciplineStore.getState().activeIds.length).toBe(1);
     });
 
     it('should activate when no prior discipline state (optimistic)', () => {
       // canProceedDiscipline returns true when disciplineState is undefined
-      useDisciplineStore.getState().activate('elemental-attunement', {
-        elements: { fire: { unlocked: false } },
+      useDisciplineStore.getState().activate('attune-fire', {
+        elements: { fire: { unlocked: false, current: 100, max: 100 } },
       });
-      expect(useDisciplineStore.getState().activeIds).toContain('elemental-attunement');
+      expect(useDisciplineStore.getState().activeIds).toContain('attune-fire');
     });
 
     it('should not activate when existing state has insufficient mana', () => {
@@ -49,10 +49,10 @@ describe('DisciplineStore', () => {
     });
 
     it('should activate when required element is unlocked', () => {
-      useDisciplineStore.getState().activate('elemental-attunement', {
-        elements: { fire: { unlocked: true } },
+      useDisciplineStore.getState().activate('attune-fire', {
+        elements: { fire: { unlocked: true, current: 100, max: 100 } },
       });
-      expect(useDisciplineStore.getState().activeIds).toContain('elemental-attunement');
+      expect(useDisciplineStore.getState().activeIds).toContain('attune-fire');
     });
   });