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/gameActions.ts

@@ -30,7 +30,7 @@ export const createResetGame = (set: (state: Partial<GameCoordinatorState>) => v
 
   useUIStore.getState().reset();
   usePrestigeStore.getState().resetPrestige();
-  useManaStore.getState().resetMana({}, {}, {}, {});
+  useManaStore.getState().resetMana({});
   useCombatStore.getState().resetCombat(startFloor);
 
   set({
@@ -43,19 +43,11 @@ export const createGatherMana = () => () => {
   const prestigeState = usePrestigeStore.getState();
   const disciplineEffects = computeDisciplineEffects();
 
-  // Compute click mana with discipline bonuses (mana-channeling → clickManaMultiplier)
-  const cm = computeClickMana(
-    {},
-    disciplineEffects,
-  );
+  // Compute click mana with discipline bonuses
+  const cm = computeClickMana(disciplineEffects);
 
   const max = computeMaxMana(
-    {
-      skills: {},
-      prestigeUpgrades: prestigeState.prestigeUpgrades,
-      skillUpgrades: {},
-      skillTiers: {}
-    },
+    { prestigeUpgrades: prestigeState.prestigeUpgrades },
     undefined,
     disciplineEffects,
   );