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.Web/Views/JournalEntries/Create.cshtml

@@ -0,0 +1,91 @@
+@model PowderCoating.Core.Entities.JournalEntry
+@{
+    ViewData["Title"] = "New Journal Entry";
+    var accounts = ViewBag.AccountSelectList as List<Microsoft.AspNetCore.Mvc.Rendering.SelectListItem>
+        ?? new List<Microsoft.AspNetCore.Mvc.Rendering.SelectListItem>();
+}
+
+<div class="d-flex align-items-center mb-3 gap-2">
+    <a asp-action="Index" class="btn btn-sm btn-outline-secondary">
+        <i class="bi bi-arrow-left me-1"></i>Back
+    </a>
+    <h4 class="mb-0 fw-semibold ms-2">New Journal Entry</h4>
+</div>
+
+@if (TempData["Error"] != null)
+{
+    <div class="alert alert-danger alert-permanent alert-dismissible fade show">
+        @TempData["Error"]
+        <button type="button" class="btn-close" data-bs-dismiss="alert"></button>
+    </div>
+}
+
+<form asp-action="Create" method="post" id="jeForm">
+    @Html.AntiForgeryToken()
+
+    <div class="card shadow-sm mb-3">
+        <div class="card-header fw-semibold">Entry Details</div>
+        <div class="card-body">
+            <div class="row g-3">
+                <div class="col-md-3">
+                    <label class="form-label fw-semibold">Date <span class="text-danger">*</span></label>
+                    <input asp-for="EntryDate" type="date" class="form-control"
+                           value="@Model.EntryDate.ToString("yyyy-MM-dd")" required />
+                </div>
+                <div class="col-md-3">
+                    <label class="form-label fw-semibold">Reference</label>
+                    <input asp-for="Reference" class="form-control" placeholder="e.g., Invoice #, memo" />
+                </div>
+                <div class="col-md-6">
+                    <label class="form-label fw-semibold">Description</label>
+                    <input asp-for="Description" class="form-control" placeholder="Brief purpose of this entry" />
+                </div>
+            </div>
+        </div>
+    </div>
+
+    <div class="card shadow-sm mb-3">
+        <div class="card-header d-flex align-items-center">
+            <span class="fw-semibold">Lines</span>
+            <div class="ms-auto d-flex gap-3 align-items-center small text-muted">
+                <span>Total Debits: <strong id="totalDebits" class="text-dark">$0.00</strong></span>
+                <span>Total Credits: <strong id="totalCredits" class="text-dark">$0.00</strong></span>
+                <span id="balanceStatus" class="badge bg-secondary">Unbalanced</span>
+            </div>
+        </div>
+        <div class="card-body p-0">
+            <table class="table table-sm mb-0" id="linesTable">
+                <thead class="table-light">
+                    <tr>
+                        <th style="width:40%">Account</th>
+                        <th>Description</th>
+                        <th class="text-end" style="width:130px">Debit</th>
+                        <th class="text-end" style="width:130px">Credit</th>
+                        <th style="width:40px"></th>
+                    </tr>
+                </thead>
+                <tbody id="linesBody">
+                    <!-- rows injected by JS -->
+                </tbody>
+            </table>
+        </div>
+        <div class="card-footer">
+            <button type="button" class="btn btn-sm btn-outline-secondary" id="addLineBtn">
+                <i class="bi bi-plus-lg me-1"></i>Add Line
+            </button>
+        </div>
+    </div>
+
+    <div class="d-flex gap-2">
+        <button type="submit" class="btn btn-primary" id="saveBtn">Save as Draft</button>
+        <a asp-action="Index" class="btn btn-outline-secondary">Cancel</a>
+    </div>
+</form>
+
+@section Scripts {
+<script src="~/js/journal-entry-create.js" asp-append-version="true"></script>
+<script>
+    JournalEntry.init(@Html.Raw(System.Text.Json.JsonSerializer.Serialize(
+        accounts.Select(a => new { value = a.Value, text = a.Text }))));
+</script>
+}