feat: add Copayment and Adjustment columns to payments table

- Added copayment and adjustment fields (Decimal, default 0) to Payment
  model in schema and directly to DB via ALTER TABLE
- Added PATCH /api/payments/:id/copayment and /adjustment routes
- Added inline-editable Copayment and Adjustment columns after MH Paid
  with same click-to-edit format; Copayment in blue, Adjustment in orange

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Backend/src/routes/payments.ts

@@ -455,6 +455,60 @@ router.patch(
   }
 );
 
+// PATCH /api/payments/:id/copayment
+router.patch(
+  "/:id/copayment",
+  async (req: Request, res: Response): Promise<any> => {
+    try {
+      const userId = req.user?.id;
+      if (!userId) return res.status(401).json({ message: "Unauthorized" });
+
+      const paymentId = parseIntOrError(req.params.id, "Payment ID");
+      const val = parseFloat(req.body.copayment);
+      if (isNaN(val) || val < 0) {
+        return res.status(400).json({ message: "Invalid copayment value" });
+      }
+
+      const updated = await prisma.payment.update({
+        where: { id: paymentId },
+        data: { copayment: val, updatedById: userId },
+      });
+
+      return res.json({ ...updated, copayment: Number(updated.copayment) });
+    } catch (err: unknown) {
+      const message = err instanceof Error ? err.message : "Failed to update copayment";
+      return res.status(500).json({ message });
+    }
+  }
+);
+
+// PATCH /api/payments/:id/adjustment
+router.patch(
+  "/:id/adjustment",
+  async (req: Request, res: Response): Promise<any> => {
+    try {
+      const userId = req.user?.id;
+      if (!userId) return res.status(401).json({ message: "Unauthorized" });
+
+      const paymentId = parseIntOrError(req.params.id, "Payment ID");
+      const val = parseFloat(req.body.adjustment);
+      if (isNaN(val) || val < 0) {
+        return res.status(400).json({ message: "Invalid adjustment value" });
+      }
+
+      const updated = await prisma.payment.update({
+        where: { id: paymentId },
+        data: { adjustment: val, updatedById: userId },
+      });
+
+      return res.json({ ...updated, adjustment: Number(updated.adjustment) });
+    } catch (err: unknown) {
+      const message = err instanceof Error ? err.message : "Failed to update adjustment";
+      return res.status(500).json({ message });
+    }
+  }
+);
+
 // PATCH /api/payments/:id/mh-payment-check
 router.patch(
   "/:id/mh-payment-check",