Phase F: Add Invoice Write-Off, Fixed Assets, Period Locking, and 1099 Tracking

- Invoice Write-Off: WriteOff POST action in InvoicesController posts bad-debt JE
  (DR bad debt expense / CR AR), reduces customer balance, marks invoice WrittenOff;
  write-off modal added to Invoice Details view with expense account selector
- Fixed Assets: FixedAsset + FixedAssetDepreciationEntry entities with straight-line
  depreciation; FixedAssetsController (Index/Create/Edit/Details/PostDepreciation/Delete);
  PostDepreciation auto-generates one JE per asset per period, skips already-posted,
  fully-depreciated, and disposed assets; full CRUD views + nav link
- Period Locking: Company.BookLockedThrough field; AccountingPeriodValidator static helper;
  lock check added to JE Post and Bill Create (blocks backdating into closed periods);
  SetPeriodLock action + date picker UI in Company Settings Accounting section
- 1099 Tracking: Is1099Vendor flag on Vendor entity + DTOs; checkbox in Create/Edit views;
  TaxReporting1099 report action + view lists payments by year, flags vendors >= $600;
  report card added to Reports Landing
- Migration AddFixedAssetsLockAnd1099 applied

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

src/PowderCoating.Web/Controllers/ReportsController.cs

@@ -2118,6 +2118,68 @@ public class ReportsController : Controller
         }
     }
 
+    // GET: /Reports/TaxReporting1099
+    /// <summary>
+    /// 1099-NEC report: sums all bill payments + expenses paid to vendors marked Is1099Vendor=true
+    /// for the selected calendar year. Flags vendors that exceed the $600 reporting threshold.
+    /// </summary>
+    public async Task<IActionResult> TaxReporting1099(int? year)
+    {
+        if (!AllowAccounting()) return RedirectToAction(nameof(Landing));
+
+        var companyId = int.TryParse(User.FindFirst("CompanyId")?.Value, out var _rcid) ? _rcid : 0;
+        var reportYear = year ?? DateTime.Now.Year;
+
+        var periodStart = new DateTime(reportYear, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        var periodEnd   = new DateTime(reportYear, 12, 31, 23, 59, 59, DateTimeKind.Utc);
+
+        // Load 1099-eligible vendors
+        var vendors = (await _unitOfWork.Vendors.FindAsync(v => v.Is1099Vendor)).ToList();
+
+        var rows = new List<Vendor1099Row>();
+
+        foreach (var vendor in vendors)
+        {
+            // Sum bills paid (using bill payment records) within the year
+            var bills = await _unitOfWork.Bills.FindAsync(
+                b => b.VendorId == vendor.Id,
+                false,
+                b => b.Payments);
+
+            decimal billPaid = bills
+                .SelectMany(b => b.Payments)
+                .Where(p => p.PaymentDate >= periodStart && p.PaymentDate <= periodEnd)
+                .Sum(p => p.Amount);
+
+            // Sum direct expenses for this vendor within the year
+            var expenses = await _unitOfWork.Expenses.FindAsync(
+                e => e.VendorId == vendor.Id && e.Date >= periodStart && e.Date <= periodEnd);
+
+            decimal expensePaid = expenses.Sum(e => e.Amount);
+
+            var total = billPaid + expensePaid;
+
+            rows.Add(new Vendor1099Row
+            {
+                VendorId    = vendor.Id,
+                VendorName  = vendor.CompanyName,
+                TaxId       = vendor.TaxId,
+                Address     = string.Join(", ", new[] { vendor.Address, vendor.City, vendor.State, vendor.ZipCode }
+                                               .Where(s => !string.IsNullOrWhiteSpace(s))),
+                BillsPaid   = billPaid,
+                ExpensesPaid = expensePaid,
+                TotalPaid   = total,
+                NeedsForm   = total >= 600m
+            });
+        }
+
+        ViewBag.ReportYear = reportYear;
+        ViewBag.AvailableYears = Enumerable.Range(DateTime.Now.Year - 5, 6).OrderDescending().ToList();
+        ViewBag.VendorsOver600 = rows.Count(r => r.NeedsForm);
+
+        return View(rows.OrderByDescending(r => r.TotalPaid).ToList());
+    }
+
     /// <summary>
     /// Looks up the current tenant's company name from the CompanyId claim. Used to inject the
     /// company name into AI prompts so the generated text refers to the actual business, not a
@@ -2245,3 +2307,15 @@ public class AnalyticsDashboardViewModel
     public int SelectedMonths { get; set; } = 6;
 }
 
+public class Vendor1099Row
+{
+    public int     VendorId     { get; set; }
+    public string  VendorName   { get; set; } = string.Empty;
+    public string? TaxId        { get; set; }
+    public string? Address      { get; set; }
+    public decimal BillsPaid    { get; set; }
+    public decimal ExpensesPaid { get; set; }
+    public decimal TotalPaid    { get; set; }
+    public bool    NeedsForm    { get; set; }
+}
+