feat: add purchase invoice batch print page and related components

- Implemented PurchaseInvoiceBatchPrintPage for printing purchase invoices.
- Created InvoicePrintHeader and InvoicePrintFooter components for invoice layout.
- Added invoice layout presets for different styles (Classic, Compact, Modern).
- Developed PurchaseInvoicePaymentDialog for handling payments against invoices.
- Introduced API mocks for company profile and invoice template configuration.
- Added validation functions for company profile and purchase invoices.
- Defined types for company profile, invoice template configuration, and purchase invoices.

Backend/ERPCore/Domain/DocumentTypes.cs

@@ -10,6 +10,7 @@ public static class DocumentTypes
     public const string Rfq = "RFQ";
     public const string PurchaseOrder = "PO";
     public const string Grn = "GRN";
+    public const string PurchaseInvoice = "PINV";
     public const string Transfer = "TRF";
     public const string Adjustment = "ADJ";
     public const string Count = "CNT";

Backend/ERPCore/Domain/Entities/Grn.cs

@@ -34,14 +34,14 @@ public class Grn
     public string? GlJournalNo { get; set; }
     public DateTime? GlPostedAt { get; set; }
 
-    /// <summary>Sum of vendor payments made against this GRN's total payable (<see cref="GrnLine.LineTotal"/>).</summary>
-    public decimal PaidAmount { get; set; }
-    /// <summary>Total payable minus <see cref="PaidAmount"/>; installments accrue against this until it reaches zero.</summary>
-    public decimal BalanceAmount { get; set; }
+    /// <summary>The Purchase Invoice this GRN has been consolidated into, if any (null until
+    /// invoiced). Vendor settlement is tracked on the invoice, not per-GRN — see
+    /// <see cref="PurchaseInvoice"/>.</summary>
+    public int? PurchaseInvoiceId { get; set; }
+    public PurchaseInvoice? PurchaseInvoice { get; set; }
 
     /// <summary>PostgreSQL xmin-backed optimistic concurrency token.</summary>
     public uint RowVersion { get; set; }
 
     public ICollection<GrnLine> Lines { get; set; } = new List<GrnLine>();
-    public ICollection<GrnPayment> Payments { get; set; } = new List<GrnPayment>();
 }

Backend/ERPCore/Domain/Entities/PurchaseInvoice.cs

@@ -0,0 +1,50 @@
+using ERPCore.Domain.Enums;
+
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// Vendor invoice consolidating one or more Confirmed GRNs for the same vendor
+/// (each linked GRN becomes one <see cref="PurchaseInvoiceLine"/>, not re-itemized).
+/// Draft is editable (GRNs can be re-selected); Posted reclassifies the GRN clearing
+/// balance to Accounts Payable (see PurchaseInvoiceService.PostAsync); vendor payments
+/// are then recorded against this aggregate rather than against the individual GRNs.
+/// </summary>
+public class PurchaseInvoice
+{
+    public int PurchaseInvoiceId { get; set; }
+    public string DocNo { get; set; } = string.Empty;
+
+    public string VendorInvoiceNo { get; set; } = string.Empty;
+    public DateTime VendorInvoiceDate { get; set; }
+
+    public int VendorId { get; set; }
+    public Vendor? Vendor { get; set; }
+
+    public string VendorSnapshotName { get; set; } = string.Empty;
+    public string? VendorSnapshotTaxNo { get; set; }
+
+    public PurchaseInvoiceStatus Status { get; set; } = PurchaseInvoiceStatus.Draft;
+
+    public decimal Subtotal { get; set; }
+    public decimal VatTotal { get; set; }
+    public decimal GrandTotal { get; set; }
+    public decimal PaidAmount { get; set; }
+    public decimal BalanceAmount { get; set; }
+
+    /// <summary>Journal number of the AP-recognition GL journal entry posted when this
+    /// invoice is Posted (Debit GRN Clearing / Credit Accounts Payable) — see
+    /// PurchaseInvoiceService.PostAsync.</summary>
+    public string? GlJournalNo { get; set; }
+    public DateTime? GlPostedAt { get; set; }
+
+    public int CreatedBy { get; set; }
+    public User? Creator { get; set; }
+
+    public DateTime CreatedAt { get; set; }
+    public DateTime? UpdatedAt { get; set; }
+
+    public uint RowVersion { get; set; }
+
+    public ICollection<PurchaseInvoiceLine> Lines { get; set; } = new List<PurchaseInvoiceLine>();
+    public ICollection<PurchaseInvoicePayment> Payments { get; set; } = new List<PurchaseInvoicePayment>();
+}

Backend/ERPCore/Domain/Entities/PurchaseInvoiceLine.cs

@@ -0,0 +1,21 @@
+namespace ERPCore.Domain.Entities;
+
+/// <summary>
+/// One row per consolidated GRN on a <see cref="PurchaseInvoice"/> — a straight
+/// consolidation of that GRN's line totals, not a re-itemization (docs: Purchase
+/// Invoice consolidates GRNs, it does not re-enter item lines).
+/// </summary>
+public class PurchaseInvoiceLine
+{
+    public int PurchaseInvoiceLineId { get; set; }
+
+    public int PurchaseInvoiceId { get; set; }
+    public PurchaseInvoice? PurchaseInvoice { get; set; }
+
+    public int GrnId { get; set; }
+    public Grn? Grn { get; set; }
+
+    public decimal Subtotal { get; set; }
+    public decimal VatTotal { get; set; }
+    public decimal LineTotal { get; set; }
+}

Backend/ERPCore/Domain/Entities/PurchaseInvoicePayment.cs

@@ -1,16 +1,17 @@
 namespace ERPCore.Domain.Entities;
 
 /// <summary>
-/// A vendor payment made against a confirmed GRN's balance (installments allowed —
-/// see GrnPaymentService.PayAsync). Posts its own real GL journal entry (Debit GRN
-/// Clearing / Credit the selected bank-or-cash account) before being recorded here.
+/// A vendor payment made against a Posted purchase invoice's balance (installments
+/// allowed — see PurchaseInvoicePaymentService.PayAsync). Posts its own real GL
+/// journal entry (Debit Accounts Payable / Credit the selected bank-or-cash account)
+/// before being recorded here.
 /// </summary>
-public class GrnPayment
+public class PurchaseInvoicePayment
 {
-    public int GrnPaymentId { get; set; }
+    public int PurchaseInvoicePaymentId { get; set; }
 
-    public int GrnId { get; set; }
-    public Grn? Grn { get; set; }
+    public int PurchaseInvoiceId { get; set; }
+    public PurchaseInvoice? PurchaseInvoice { get; set; }
 
     public decimal Amount { get; set; }
     public DateTime PaymentDate { get; set; }

Backend/ERPCore/Domain/Entities/SalesInvoicePayment.cs

@@ -4,7 +4,7 @@ namespace ERPCore.Domain.Entities;
 /// A customer payment made against a Posted sales invoice's balance (installments
 /// allowed — see SalesInvoicePaymentService.PayAsync). Posts its own real GL journal
 /// entry (Debit the selected bank-or-cash account / Credit Accounts Receivable) before
-/// being recorded here — the mirror image of <see cref="GrnPayment"/>.
+/// being recorded here — the mirror image of <see cref="PurchaseInvoicePayment"/>.
 /// </summary>
 public class SalesInvoicePayment
 {

Backend/ERPCore/Domain/Enums/PurchaseInvoiceStatus.cs

@@ -0,0 +1,8 @@
+namespace ERPCore.Domain.Enums;
+
+public enum PurchaseInvoiceStatus
+{
+    Draft,
+    Posted,
+    Cancelled
+}