refactor: remove skill system leftovers, migrate click mana to discipline perk

- Simplified getMeditationBonus() to continuous ramp formula
- Added click-mana capped perk to Mana Circulation discipline
- Removed manaWell/manaFlow/manaSpring skill reads and prestige upgrades
- Removed all skill fields from GameState and GameActionType
- Updated all call sites and tests (916 tests passing)

Closes #174

src/lib/game/stores/combat-actions.ts

@@ -96,7 +96,7 @@ export function processCombatTick(
       // Calculate base damage
       const floorElement = getFloorElement(currentFloor);
       const damage = calcDamage(
-        { skills: {}, signedPacts },
+        { signedPacts },
         spellId,
         floorElement,
         disciplineEffects,
@@ -151,7 +151,7 @@ export function processCombatTick(
         // Calculate damage
         const eFloorElement = getFloorElement(currentFloor);
         const eDamage = calcDamage(
-          { skills: {}, signedPacts },
+          { signedPacts },
           eSpell.spellId,
           eFloorElement,
           disciplineEffects,