Fix: Checkbox value binding for IsActive field

Fixed checkbox to send proper boolean values:
- Added value="true" to checkbox input
- Added hidden field with value="false" for unchecked state
- When unchecked: sends "false" from hidden field
- When checked: sends "true" from checkbox (overrides hidden field)

This follows standard ASP.NET checkbox binding pattern.

🤖 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 +38,8 @@
 
                     <div class="mb-3">
                         <div class="form-check">
-                            <input name="IsActive" id="IsActive" class="form-check-input" type="checkbox" @(Model.IsActive == true ? "checked" : "") />
+                            <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
                             </label>