fix: remove discipline pool-drain model, add conversion stats UI per mana-conversion-spec

DISC-2: Removed old pool-drain model from discipline-slice.ts processTick()
- Disciplines no longer drain rawMana or element pools
- canProceedDiscipline() no longer checks mana sufficiency
- Removed auto-pause on insufficient mana from processTick()
- Removed drain display and auto-paused message from DisciplineCard.tsx
- Removed auto-paused log from gameStore.ts tick()

DISC-4: Audited crafting pipeline — no composite crafting logic remains
- craftComposite already removed from manaStore.ts (comment only)
- No other composite crafting references found

DISC-5: Added collapsible formula reference to Conversion Stats section
- Shows unified formula, multipliers, cost formulas, and constraints

DISC-6: Added per-element net regen summary line
- Shows 'Net Fire Regen: +0.50/hr − 0.15/hr = +0.35/hr' per element

DISC-7: Created dedicated 'Conversion Stats' section in Stats tab
- Renamed from 'Conversion Breakdown' to dedicated section header

DISC-8: Added detailed per-element regen breakdown to ManaDisplay
- Each element card now expandable to show produced rate and downstream drains
- New ElementRegenBreakdown type and elementRegenBreakdown prop

Tests: Updated 4 test files to reflect new no-drain behavior
- All 1090 tests pass

src/lib/game/stores/discipline-slice.ts

@@ -5,7 +5,6 @@ import { createSafeStorage } from '../utils/safe-persist';
 import type { DisciplineState } from '../types/disciplines';
 import type { ElementState } from '../types';
 import {
-  calculateManaDrain,
   calculateStatBonus,
   canProceedDiscipline,
   checkDisciplinePrerequisites,
@@ -171,7 +170,7 @@ export const useDisciplineStore = create<DisciplineStore>()(
 
       processTick(mana) {
         const s = get();
-        let rawMana = mana.rawMana;
+        const rawMana = mana.rawMana;
         const elements = { ...mana.elements };
         let newXP = s.totalXP;
         const newDisciplines = { ...s.disciplines };
@@ -179,8 +178,6 @@ export const useDisciplineStore = create<DisciplineStore>()(
         const newUnlockedRecipes: string[] = [];
         const newProcessedPerks = [...(s.processedPerks ?? [])];
 
-        const drainedIds: string[] = [];
-        const drainedNames: string[] = [];
         for (const id of s.activeIds ?? []) {
           const disc = newDisciplines[id];
           if (!disc) continue;
@@ -190,26 +187,6 @@ export const useDisciplineStore = create<DisciplineStore>()(
           const def = DISCIPLINE_MAP[id];
           if (!def) continue;
 
-          const drain = calculateManaDrain(def.drainBase, disc.xp, def.difficultyFactor);
-          const element = elements[def.manaType];
-          const available = def.manaType === 'raw' ? rawMana : element?.current;
-
-          if (!available || available < drain) {
-            newDisciplines[id] = { ...disc, paused: true, autoPaused: true };
-            drainedIds.push(id);
-            drainedNames.push(def.name);
-            continue;
-          }
-
-          if (def.manaType === 'raw') {
-            rawMana -= drain;
-          } else if (elements[def.manaType]) {
-            elements[def.manaType] = {
-              ...elements[def.manaType],
-              current: elements[def.manaType].current - drain,
-            };
-          }
-
           const oldXP = disc.xp;
           // Compute discipline XP bonus directly to avoid circular import
           let xpBonus = 0;
@@ -264,21 +241,21 @@ export const useDisciplineStore = create<DisciplineStore>()(
           MAX_CONCURRENT_DISCIPLINES + 3
         );
 
-        // Remove mana-drained disciplines from activeIds so onStopPracticing fires
-        const newActiveIds = (s.activeIds ?? []).filter((aid) => !drainedIds.includes(aid));
-        if (newActiveIds.length === 0 && s.activeIds.length > 0) {
+        // Check if no active disciplines remain to fire onStopPracticing
+        const keepActiveIds = s.activeIds ?? [];
+        if (keepActiveIds.length === 0 && s.activeIds.length > 0) {
           get().practicingCallbacks?.onStopPracticing?.();
         }
 
         set({
           disciplines: newDisciplines,
-          activeIds: newActiveIds,
+          activeIds: keepActiveIds,
           totalXP: newXP,
           concurrentLimit: Math.max(s.concurrentLimit, newLimit),
           processedPerks: newProcessedPerks,
         });
 
-        return { rawMana, elements, unlockedEffects: newUnlockedEffects, unlockedRecipes: newUnlockedRecipes, autoPausedNames: drainedNames };
+        return { rawMana, elements, unlockedEffects: newUnlockedEffects, unlockedRecipes: newUnlockedRecipes, autoPausedNames: [] };
       },
     }),
     { storage: createSafeStorage(), name: 'mana-loop-discipline-store', version: 1, partialize: (state) => ({ disciplines: state.disciplines, activeIds: state.activeIds, concurrentLimit: state.concurrentLimit, totalXP: state.totalXP, processedPerks: state.processedPerks }) }