fix: deduct component consumption from element pools in mana conversion

Bug #293: elementDrain was computed but never subtracted from element pools.
The tick pipeline now applies net regen (produced - drained) instead of
gross production to element pools, matching the spec §8 regen deduction model.

docs/project-structure.txt

@@ -229,6 +229,7 @@ Mana-Loop/
 │   │   │   │   ├── formatting.test.ts
 │   │   │   │   ├── guardian-names.test.ts
 │   │   │   │   ├── hasty-enchanter.test.ts
+│   │   │   │   ├── mana-conversion-component-deduction.test.ts
 │   │   │   │   ├── mana-utils.test.ts
 │   │   │   │   ├── melee-auto-attack.test.ts
 │   │   │   │   ├── melee-defense-bypass.test.ts