Fix: Categories Edit - nullable bool conversion error

Fixed type conversion error in Categories/Edit.cshtml where Model.IsActive (bool?)
was being evaluated in a ternary operator that requires non-nullable bool.

Changed from: @(Model.IsActive ? "checked" : "")
To: @(Model.IsActive == true ? "checked" : "")

This properly handles null, false, and true values for the checkbox.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

LittleShop/Areas/Admin/Views/Categories/Edit.cshtml

@@ -38,7 +38,7 @@
 
                     <div class="mb-3">
                         <div class="form-check">
-                            <input name="IsActive" id="IsActive" class="form-check-input" type="checkbox" @(Model.IsActive ? "checked" : "") />
+                            <input name="IsActive" id="IsActive" class="form-check-input" type="checkbox" @(Model.IsActive == true ? "checked" : "") />
                             <label for="IsActive" class="form-check-label">
                                 Active
                             </label>