fix: split multi-type golem core upkeep across all mana types (issue #315)

src/lib/game/data/golems/golemancy-data.test.ts

@@ -186,11 +186,49 @@ describe('Computed stats', () => {
     const design = makeDesign('basic', 'earth', 'simple');
     const stats = computeGolemStats(design);
 
+    // Basic core has 1 mana type (earth), so all upkeep goes to earth
     expect(stats.upkeepCostPerHour.length).toBe(1);
     expect(stats.upkeepCostPerHour[0].amount).toBe(1.0);
     expect(stats.upkeepCostPerHour[0].element).toBe('earth');
   });
 
+  it('multi-type core splits upkeep evenly across selected mana types', () => {
+    const design = makeDesign('intermediate', 'earth', 'simple');
+    design.selectedManaTypes = ['fire', 'water'];
+    const stats = computeGolemStats(design);
+
+    // Intermediate core: manaRegen=1.5, upkeep=3.0/hr split across 2 types = 1.5 each
+    expect(stats.upkeepCostPerHour.length).toBe(2);
+    expect(stats.upkeepCostPerHour[0].element).toBe('fire');
+    expect(stats.upkeepCostPerHour[0].amount).toBe(1.5);
+    expect(stats.upkeepCostPerHour[1].element).toBe('water');
+    expect(stats.upkeepCostPerHour[1].amount).toBe(1.5);
+  });
+
+  it('advanced core (3 types) splits upkeep three ways', () => {
+    const design = makeDesign('advanced', 'steel', 'simple');
+    design.selectedManaTypes = ['fire', 'water', 'earth'];
+    const stats = computeGolemStats(design);
+
+    // Advanced core: manaRegen=3.0, upkeep=6.0/hr split across 3 types = 2.0 each
+    expect(stats.upkeepCostPerHour.length).toBe(3);
+    const totalUpkeep = stats.upkeepCostPerHour.reduce((sum, c) => sum + c.amount, 0);
+    expect(totalUpkeep).toBe(6.0);
+    for (const cost of stats.upkeepCostPerHour) {
+      expect(cost.amount).toBe(2.0);
+    }
+  });
+
+  it('single-type core does not split upkeep', () => {
+    const design = makeDesign('basic', 'earth', 'simple');
+    // Basic core has manaTypes=['earth'], selectedManaTypes=[] => uses core.manaTypes
+    const stats = computeGolemStats(design);
+
+    expect(stats.upkeepCostPerHour.length).toBe(1);
+    expect(stats.upkeepCostPerHour[0].amount).toBe(1.0); // 0.5 * 2 = 1.0
+    expect(stats.upkeepCostPerHour[0].element).toBe('earth');
+  });
+
   it('selected mana types override core defaults', () => {
     const design = makeDesign('intermediate', 'earth', 'simple');
     design.selectedManaTypes = ['fire', 'water'];