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/gameHooks.ts

@@ -33,8 +33,6 @@ export function useUnifiedEffects() {
 
   return {
     ...getUnifiedEffects({
-      skillUpgrades: {},
-      skillTiers: {},
       equippedInstances,
       equipmentInstances,
     }),
@@ -55,27 +53,25 @@ export function useManaStats() {
   const disciplineEffects = computeDisciplineEffects();
 
   const upgradeEffects = getUnifiedEffects({
-    skillUpgrades: {},
-    skillTiers: {},
     equippedInstances,
     equipmentInstances,
   });
 
   const maxMana = computeMaxMana(
-    { skills: {}, prestigeUpgrades, skillUpgrades: {}, skillTiers: {} },
+    { prestigeUpgrades },
     upgradeEffects,
     disciplineEffects,
   );
 
   const baseRegen = computeRegen(
-    { skills: {}, prestigeUpgrades, skillUpgrades: {}, skillTiers: {}, attunements: {} },
+    { prestigeUpgrades, attunements: {} },
     upgradeEffects,
     disciplineEffects,
   );
 
-  const clickMana = computeClickMana({}, disciplineEffects);
+  const clickMana = computeClickMana(disciplineEffects);
 
-  const meditationMultiplier = getMeditationBonus(meditateTicks, {}, upgradeEffects.meditationEfficiency, disciplineEffects.meditationCapBonus);
+  const meditationMultiplier = getMeditationBonus(meditateTicks, upgradeEffects.meditationEfficiency, disciplineEffects.meditationCapBonus);
   const incursionStrength = getIncursionStrength(day, hour);
   const effectiveRegenWithSpecials = baseRegen * (1 - incursionStrength);
 
@@ -113,8 +109,6 @@ export function useCombatStats() {
   const equipmentInstances = useCraftingStore((s) => s.equipmentInstances);
 
   const upgradeEffects = getUnifiedEffects({
-    skillUpgrades: {},
-    skillTiers: {},
     equippedInstances,
     equipmentInstances,
   });