fix: totalAmount always stores grand total including GST

manager-line-edit-actions: add gstRate to lineItemSchema; recalculate
newTotal as sum(qty * unitPrice * (1 + gstRate)) and persist gstRate
on recreated line items.

seed: patch existing POs totalAmount to grand total (taxable * 1.18):
  PO-2026-00001: 8450 -> 9971
  PO-2026-00002: 3200 -> 3776
  PO-2026-00003:  950 -> 1121

App/pelagia-portal/app/(portal)/approvals/[id]/manager-line-edit-actions.ts

@@ -14,6 +14,7 @@ const lineItemSchema = z.object({
   unit: z.string().min(1),
   size: z.string().optional(),
   unitPrice: z.coerce.number().nonnegative(),
+  gstRate: z.coerce.number().min(0).max(1).default(0.18),
 });
 
 export async function managerEditLineItems({
@@ -46,7 +47,10 @@ export async function managerEditLineItems({
     unitPrice: Number(li.unitPrice),
   }));
 
-  const newTotal = parsed.data.reduce((sum, item) => sum + item.quantity * item.unitPrice, 0);
+  const newTotal = parsed.data.reduce(
+    (sum, item) => sum + item.quantity * item.unitPrice * (1 + item.gstRate),
+    0
+  );
 
   await db.purchaseOrder.update({
     where: { id: poId },
@@ -61,6 +65,7 @@ export async function managerEditLineItems({
           size: item.size ?? null,
           unitPrice: item.unitPrice,
           totalPrice: item.quantity * item.unitPrice,
+          gstRate: item.gstRate,
           sortOrder: idx,
         })),
       },

App/pelagia-portal/prisma/seed.ts

@@ -188,12 +188,12 @@ async function main() {
   // Sample POs — upsert so re-running seed is safe
   const po1 = await db.purchaseOrder.upsert({
     where: { poNumber: "PO-2026-00001" },
-    update: { currency: "INR" },
+    update: { currency: "INR", totalAmount: 9971.0 },
     create: {
       poNumber: "PO-2026-00001",
       title: "Engine Room Spare Parts — MV Pelagia Star",
       status: "MGR_REVIEW",
-      totalAmount: 8450.0,
+      totalAmount: 9971.0, // 8450 taxable × 1.18 GST
       currency: "INR",
       submittedAt: new Date(),
       submitterId: technical.id,
@@ -218,12 +218,12 @@ async function main() {
 
   await db.purchaseOrder.upsert({
     where: { poNumber: "PO-2026-00002" },
-    update: { currency: "INR" },
+    update: { currency: "INR", totalAmount: 3776.0 },
     create: {
       poNumber: "PO-2026-00002",
       title: "Crew Safety Equipment — MV Aegean Wind",
       status: "DRAFT",
-      totalAmount: 3200.0,
+      totalAmount: 3776.0, // 3200 taxable × 1.18 GST
       currency: "INR",
       submitterId: technical.id,
       vesselId: mv2.id,
@@ -242,12 +242,12 @@ async function main() {
 
   await db.purchaseOrder.upsert({
     where: { poNumber: "PO-2026-00003" },
-    update: { currency: "INR" },
+    update: { currency: "INR", totalAmount: 1121.0 },
     create: {
       poNumber: "PO-2026-00003",
       title: "Navigation Charts Update — Fleet",
       status: "MGR_APPROVED",
-      totalAmount: 950.0,
+      totalAmount: 1121.0, // 950 taxable × 1.18 GST
       currency: "INR",
       submittedAt: new Date(Date.now() - 5 * 86400000),
       approvedAt: new Date(Date.now() - 2 * 86400000),