fix: resolve all 8 open bug tickets (#242–#249) (#250)

## Summary

- **#242** — Crystals in the resource bar now use `formatNumber` to respect the player's notation setting (suffix/scientific/engineering)
- **#243** — Companion unlock progress includes current-run gold (`totalGoldEarned`) on both client and server, so companions unlock at the correct threshold
- **#244** — Empty green reward bubbles no longer render for quest crystal rewards with a zero amount
- **#245/#248** — Auto-save skips when `isAutoPrestigingReference.current` is true, preventing it from racing with an in-flight prestige and breaking the optimistic lock
- **#246** — Generated and uploaded CDN images for `crystal_pulse`, `crystal_surge`, and `crystal_tempest` upgrades
- **#247** — `validateAndSanitize` merges daily challenge progress by taking the max of client vs. server progress per challenge, so stale auto-saves can no longer roll back server-side completions
- **#249** — Cached save signature is cleared after `buyPrestigeUpgrade` succeeds, preventing a stale-signature mismatch on the next auto-save

## Test plan

- [ ] Lint passes (`pnpm lint`)
- [ ] Build passes (`pnpm build`)
- [ ] Tests pass with 100% coverage (`pnpm test`)
- [ ] Crystals display in resource bar respects notation setting
- [ ] No empty reward bubbles on quests that don't award crystals
- [ ] Companion progress bar shows correct value including current-run gold
- [ ] Auto-prestige no longer causes save errors
- [ ] Crafting a recipe updates daily challenge progress persistently (not rolled back by next auto-save)
- [ ] Buying a prestige upgrade does not cause a signature mismatch error on next save
- [ ] Crystal upgrade images display correctly in-game

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #250
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

apps/web/src/components/game/questPanel.tsx

@@ -114,6 +114,9 @@ const QuestCard = ({
         }
         <div className="quest-rewards">
           {quest.rewards.map((reward, rewardIndex) => {
+            if (reward.type === "crystals" && (reward.amount ?? 0) === 0) {
+              return null;
+            }
             return (
               <span className="reward-tag" key={`${reward.type}-${reward.targetId ?? String(reward.amount ?? rewardIndex)}`}>
                 {reward.type === "gold"
@@ -121,7 +124,6 @@ const QuestCard = ({
                 {reward.type === "essence"
                   && `✨ ${formatNumber(reward.amount ?? 0)}`}
                 {reward.type === "crystals"
-                  && (reward.amount ?? 0) > 0
                   && `💎 ${formatNumber(reward.amount ?? 0)}`}
                 {reward.type === "upgrade" && "🔓 Upgrade"}
                 {reward.type === "adventurer" && "👥 New Adventurer"}