Fix: Categories Edit IsActive checkbox now works both ways

Fixed two issues preventing IsActive toggle:
1. Removed hidden field that was sending "false" even when checkbox checked
2. Updated CategoryService to always update IsActive, treating null as false

Checkbox behavior:
- Checked → sends "true" → IsActive = true
- Unchecked → sends nothing (null) → IsActive = false (via ?? operator)

This allows both setting inactive→active and active→inactive.

🤖 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 +38,6 @@
 
                     <div class="mb-3">
                         <div class="form-check">
-                            <input type="hidden" name="IsActive" value="false" />
                             <input name="IsActive" id="IsActive" class="form-check-input" type="checkbox" value="true" @(Model.IsActive == true ? "checked" : "") />
                             <label for="IsActive" class="form-check-label">
                                 Active

LittleShop/Services/CategoryService.cs

@@ -89,10 +89,8 @@ public class CategoryService : ICategoryService
             category.Description = updateCategoryDto.Description;
         }
 
-        if (updateCategoryDto.IsActive.HasValue)
+        // Always update IsActive - treat null (unchecked) as false
-        {
+        category.IsActive = updateCategoryDto.IsActive ?? false;
-            category.IsActive = updateCategoryDto.IsActive.Value;
-        }
 
         await _context.SaveChangesAsync();
         return true;