Phase C: Add Manual Journal Entries (double-entry GL)

- JournalEntry + JournalEntryLine entities with Draft/Posted/Reversed lifecycle
- JournalEntryStatus enum (Draft, Posted, Reversed)
- Migration AddJournalEntries: two new tables with self-referencing reversal FK
- IUnitOfWork/UnitOfWork wired with JournalEntries + JournalEntryLines repos
- ApplicationDbContext: DbSets, tenant query filters, reversal FK config
- LedgerService: JE lines added as 10th source in GetAccountLedgerAsync and ComputePriorBalanceAsync
- JournalEntriesController: Index (All/Draft/Posted tabs), Create, Details, Post, Reverse, Delete
- Views: Index, Create (dynamic balanced line grid with running debit/credit totals), Details
- journal-entry-create.js: dynamic line management with balance indicator
- Nav: Journal Entries added to Finance section in _Layout

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

src/PowderCoating.Infrastructure/Data/ApplicationDbContext.cs

@@ -324,6 +324,11 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
     /// <summary>Ad-hoc expense records (non-bill spending); tenant-filtered with soft delete.</summary>
     public DbSet<Expense> Expenses { get; set; }
 
+    /// <summary>Manual double-entry journal entries (Draft/Posted/Reversed lifecycle); tenant-filtered with soft delete.</summary>
+    public DbSet<JournalEntry> JournalEntries { get; set; }
+    /// <summary>Individual debit/credit lines within a journal entry; soft-delete only (access controlled through parent JournalEntry).</summary>
+    public DbSet<JournalEntryLine> JournalEntryLines { get; set; }
+
     // Job Templates
     /// <summary>Reusable job templates that pre-populate job items, coats, and prep services on job creation.</summary>
     public DbSet<JobTemplate> JobTemplates { get; set; }
@@ -614,6 +619,11 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
         modelBuilder.Entity<Expense>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
 
+        // Journal Entries: tenant-filtered; lines use soft-delete only (child rows)
+        modelBuilder.Entity<JournalEntry>().HasQueryFilter(e =>
+            !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
+        modelBuilder.Entity<JournalEntryLine>().HasQueryFilter(e => !e.IsDeleted);
+
         // Purchase Orders
         modelBuilder.Entity<PurchaseOrder>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
@@ -633,6 +643,13 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
             .HasForeignKey(a => a.ParentAccountId)
             .OnDelete(DeleteBehavior.Restrict);
 
+        // JournalEntry self-referencing reversal link
+        modelBuilder.Entity<JournalEntry>()
+            .HasOne(je => je.ReversalOf)
+            .WithMany()
+            .HasForeignKey(je => je.ReversalOfId)
+            .OnDelete(DeleteBehavior.Restrict);
+
         // Vendor → DefaultExpenseAccount (no cascade)
         modelBuilder.Entity<Vendor>()
             .HasOne(s => s.DefaultExpenseAccount)