feat: another balance and bug fix pass (#238)

Working through open issues — fixes, balance changes, and features.

## Closed

- Closes #161
- Closes #181
- Closes #191
- Closes #199
- Closes #201
- Closes #202
- Closes #203
- Closes #204
- Closes #205
- Closes #206
- Closes #208
- Closes #211
- Closes #212
- Closes #213
- Closes #214
- Closes #216
- Closes #219
- Closes #220
- Closes #221
- Closes #222
- Closes #224
- Closes #225
- Closes #226
- Closes #228
- Closes #229
- Closes #230
- Closes #231
- Closes #232
- Closes #233
- Closes #234
- Closes #235
- Closes #236

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #238
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

apps/api/src/services/prestige.ts

@@ -28,8 +28,8 @@ const maxBaseRunestones = 200;
 
 /**
  * Calculates the gold threshold required for the next prestige.
- * Formula: BASE * (count + 1)^2 — polynomial growth that peaks around prestige 8–10
- * then gets easier as the production multiplier overtakes it.
+ * Formula: BASE * (count + 1)^2.5 — steeper growth to keep late prestiges
+ * meaningful even as the production multiplier scales.
  * @param prestigeCount - The current number of prestiges completed.
  * @param thresholdMultiplier - An optional echo-upgrade multiplier applied to the threshold.
  * @returns The gold amount required to prestige.
@@ -40,7 +40,7 @@ const calculatePrestigeThreshold = (
 ): number => {
   return (
     basePrestigeGoldThreshold
-    * Math.pow(prestigeCount + 1, 2)
+    * Math.pow(prestigeCount + 1, 2.5)
     * thresholdMultiplier
   );
 };
@@ -189,6 +189,7 @@ const buildPostPrestigeState = (
 } => {
   const {
     autoPrestigeEnabled,
+    autoPrestigeMaxRunestonesOnly,
     count:              currentPrestigeCount,
     purchasedUpgradeIds,
     runestones:         currentRunestones,
@@ -215,6 +216,9 @@ const buildPostPrestigeState = (
     ...autoPrestigeEnabled === undefined
       ? {}
       : { autoPrestigeEnabled },
+    ...autoPrestigeMaxRunestonesOnly === undefined
+      ? {}
+      : { autoPrestigeMaxRunestonesOnly },
   };
 
   const freshState = initialGameState(currentState.player, characterName);