fix: apply mana drain to conversion disciplines (bug #379)

- Remove isConversionDiscipline guard in discipline-slice.ts:processTick
  that was skipping mana drain for all 24 conversion disciplines
- Update test to verify conversion disciplines DO drain mana
- Add regression tests for auto-pause and XP accrual on conversion disciplines
- Fix misleading comments in elemental-regen.ts and elemental-regen-advanced.ts

All 1196 tests pass.

src/lib/game/__tests__/store-actions-discipline.test.ts

@@ -131,7 +131,7 @@ describe('DisciplineStore', () => {
       expect(result.elements.fire.current).toBe(98);
     });
 
-    it('should not drain mana for conversion disciplines (sourceManaTypes)', () => {
+    it('should drain mana for conversion disciplines (regression: was zero cost)', () => {
       useDisciplineStore.setState({
         disciplines: {},
         activeIds: [],
@@ -139,13 +139,45 @@ describe('DisciplineStore', () => {
         totalXP: 0,
       });
       // regen-fire is a conversion discipline with sourceManaTypes: ['raw']
+      // It has manaType='fire' and drainBase=1.5 — it MUST drain fire mana
       useDisciplineStore.getState().activate('regen-fire', {
         elements: { fire: { unlocked: true, current: 100, max: 100, baseMax: 100 } },
       });
       const result = useDisciplineStore.getState().processTick({ rawMana: 1000, elements: { fire: { unlocked: true, current: 100, max: 100, baseMax: 100 } } });
-      // Conversion disciplines should NOT drain from pools
-      expect(result.rawMana).toBe(1000);
-      expect(result.elements.fire.current).toBe(100);
+      // Conversion disciplines MUST drain from their mana pool (bug fix #379)
+      // regen-fire: drainBase=1.5, xp=0, difficultyFactor=120
+      // drain = 1.5 * (1 + (0/120)^0.4) = 1.5
+      expect(result.elements.fire.current).toBeCloseTo(98.5, 1);
+    });
+
+    it('should auto-pause conversion discipline when element mana is insufficient', () => {
+      useDisciplineStore.setState({
+        disciplines: {},
+        activeIds: [],
+        concurrentLimit: 1,
+        totalXP: 0,
+      });
+      // regen-fire has drainBase=1.5, needs at least 1.5 fire mana
+      useDisciplineStore.getState().activate('regen-fire', {
+        elements: { fire: { unlocked: true, current: 1, max: 100, baseMax: 100 } },
+      });
+      const result = useDisciplineStore.getState().processTick({ rawMana: 1000, elements: { fire: { unlocked: true, current: 1, max: 100, baseMax: 100 } } });
+      expect(useDisciplineStore.getState().disciplines['regen-fire'].autoPaused).toBe(true);
+      expect(result.autoPausedNames).toContain('Fire Mana Conversion Speed');
+    });
+
+    it('should still accrue XP for conversion disciplines when mana is sufficient', () => {
+      useDisciplineStore.setState({
+        disciplines: {},
+        activeIds: [],
+        concurrentLimit: 1,
+        totalXP: 0,
+      });
+      useDisciplineStore.getState().activate('regen-fire', {
+        elements: { fire: { unlocked: true, current: 100, max: 100, baseMax: 100 } },
+      });
+      useDisciplineStore.getState().processTick({ rawMana: 1000, elements: { fire: { unlocked: true, current: 100, max: 100, baseMax: 100 } } });
+      expect(useDisciplineStore.getState().disciplines['regen-fire'].xp).toBe(1);
     });
 
     it('should re-activate auto-paused discipline when mana is restored', () => {

src/lib/game/data/disciplines/elemental-regen-advanced.ts

@@ -4,7 +4,7 @@
 //
 // NEW MODEL: Disciplines contribute to conversion_{element} stat bonus.
 // The unified conversion-rates.ts calculator handles rate computation.
-// No direct mana drain — costs are deducted from regen.
+// Mana drain is applied from the target mana type pool each tick.
 
 import { DisciplinesAttunementType } from '../../types/disciplines';
 import type { DisciplineDefinition } from '../../types/disciplines';

src/lib/game/data/disciplines/elemental-regen.ts

@@ -4,7 +4,7 @@
 //
 // NEW MODEL: Disciplines contribute to conversion_{element} stat bonus.
 // The unified conversion-rates.ts calculator handles rate computation.
-// No direct mana drain — costs are deducted from regen.
+// Mana drain is applied from the target mana type pool each tick.
 
 import { DisciplinesAttunementType } from '../../types/disciplines';
 import type { DisciplineDefinition } from '../../types/disciplines';

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

@@ -212,13 +212,11 @@ export const useDisciplineStore = create<DisciplineStore>()(
           const def = DISCIPLINE_MAP[id];
           if (!def) continue;
 
-          // ── Mana drain (skip for conversion disciplines) ──────────────
-          // Conversion disciplines (with sourceManaTypes) are handled by
-          // the unified conversion system — they contribute to conversion
-          // rates, not direct pool drain.
-          const isConversionDiscipline = !!(def.sourceManaTypes && def.sourceManaTypes.length > 0);
-
-          if (!isConversionDiscipline) {
+          // ── Mana drain ──────────────────────────────────────────────────
+          // All disciplines (including conversion) drain from their mana pool.
+          // Conversion disciplines both drain their target mana type AND
+          // contribute to conversion rates.
+          {
             const drain = calculateManaDrain(def.drainBase, disc.xp, def.difficultyFactor);
 
             // Determine which mana pool to drain from