feat(admin): discount edit/delete + project-scoped scene/color editor

Identity (discounts):
- DiscountsController: PUT /v1/discounts/{id}, DELETE /v1/discounts/{id}
- DiscountService.UpdateAsync (partial update, code-clash guard) + DeleteAsync
- UpdateDiscountRequest record (all fields optional incl. is_active)
- Frontend discountsConfig: canEdit + canDelete + is_active field

Content (scenes/colors — UI for existing CRUD endpoints):
- New SceneColorEditor.tsx: 3-tab modal (scenes / shared-colors / color-presets),
  project-scoped, full add/edit/delete per tab, colour pickers + palette item editor
- Wired into TemplatesAdmin: "صحنه‌ها و رنگ‌ها" button per template variant row
- Routes through the generic admin proxy with ?project_id=

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/identity/FlatRender.IdentitySvc/Controllers/DiscountsController.cs

@@ -37,6 +37,22 @@ public class DiscountsController(IDiscountService discountService) : ControllerB
         return StatusCode(201, result);
     }
 
+    [HttpPut("{id:guid}")]
+    [ProducesResponseType(typeof(DiscountResponse), 200)]
+    public async Task<IActionResult> Update(Guid id, [FromBody] UpdateDiscountRequest request)
+    {
+        var result = await discountService.UpdateAsync(GetTenantId(), id, request);
+        return result == null ? NotFound() : Ok(result);
+    }
+
+    [HttpDelete("{id:guid}")]
+    [ProducesResponseType(204)]
+    public async Task<IActionResult> Delete(Guid id)
+    {
+        var ok = await discountService.DeleteAsync(GetTenantId(), id);
+        return ok ? NoContent() : NotFound();
+    }
+
     private Guid GetTenantId() => Guid.Parse(User.FindFirst("tenant_id")?.Value
         ?? throw new UnauthorizedAccessException());