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/test/routes/game.spec.ts

@@ -477,6 +477,28 @@ describe("game route", () => {
       expect(body.savedAt).toBeGreaterThan(0);
     });
 
+    it("restores previous upgrades when incoming prestige count is lower (stale post-prestige save)", async () => {
+      const prevUpgrades = [
+        { id: "click_1", purchased: false, unlocked: true, target: "click", multiplier: 2 },
+      ] as GameState["upgrades"];
+      const prevState = makeState({
+        prestige: { count: 1, runestones: 10, productionMultiplier: 1.3, purchasedUpgradeIds: [] },
+        upgrades: prevUpgrades,
+      });
+      const incomingState = makeState({
+        prestige: { count: 0, runestones: 0, productionMultiplier: 1, purchasedUpgradeIds: [] },
+        upgrades: [
+          { id: "click_1", purchased: true, unlocked: true, target: "click", multiplier: 2 },
+        ] as GameState["upgrades"],
+      });
+      vi.mocked(prisma.gameState.findUnique).mockResolvedValueOnce({ state: prevState } as never);
+      vi.mocked(prisma.player.findUnique).mockResolvedValueOnce(makePlayer({ createdAt: Date.now() }) as never);
+      vi.mocked(prisma.player.update).mockResolvedValueOnce({} as never);
+      vi.mocked(prisma.gameState.upsert).mockResolvedValueOnce({} as never);
+      const res = await save({ state: incomingState });
+      expect(res.status).toBe(200);
+    });
+
     it("validates companion when active companion is legitimately unlocked", async () => {
       const prevState = makeState();
       const stateWithCompanion = makeState({