Add Banner example and integration test

Updated Banner documentation to include a new example image and code snippet. Added an integration test and golden image for Banner control to improve test coverage and documentation clarity.

Author: InesaFitsner

sdk/python/packages/flet/docs/controls/banner.md

@@ -1,10 +1,11 @@
 ---
 class_name: flet.Banner
 examples: ../../examples/controls/banner
-example_images: ../examples/controls/banner/media
+example_images: ../test-images/examples/material/golden/macos/banner
+example_media: ../examples/controls/banner/media
 ---
 
-{{ class_summary(class_name) }}
+{{ class_summary(class_name, example_images + "/image_for_docs.png", image_caption="Basic Banner") }}
 
 ## Examples
 
@@ -16,7 +17,7 @@ example_images: ../examples/controls/banner/media
 --8<-- "{{ examples }}/basic.py"
 ```
 
-{{ image(example_images + "/basic.gif", alt="basic", width="80%") }}
+{{ image(example_media + "/basic.gif", alt="basic", width="80%") }}
 
 
 {{ class_members(class_name) }}

sdk/python/packages/flet/integration_tests/examples/material/golden/macos/banner/image_for_docs.png

@@ -0,0 +1,30 @@
+import pytest
+
+import flet as ft
+import flet.testing as ftt
+
+
+@pytest.mark.asyncio(loop_scope="function")
+async def test_image_for_docs(flet_app_function: ftt.FletTestApp, request):
+    page = flet_app_function.page
+    page.theme_mode = ft.ThemeMode.LIGHT
+    page.enable_screenshots = True
+    page.window.width = 400
+    page.window.height = 200
+    banner = ft.Banner(
+        leading=ft.Icon(ft.Icons.INFO_OUTLINED, color=ft.Colors.PRIMARY),
+        content=ft.Text("Backup completed successfully."),
+        actions=[ft.TextButton("Dismiss")],
+        bgcolor=ft.Colors.SURFACE_CONTAINER_LOW,
+        open=True,
+    )
+    page.add(banner)
+    page.update()
+    await flet_app_function.tester.pump_and_settle()
+    flet_app_function.assert_screenshot(
+        "test_image_for_docs",
+        await flet_app_function.page.take_screenshot(
+            pixel_ratio=flet_app_function.screenshots_pixel_ratio
+        ),
+    )
+    page.update()

sdk/python/packages/flet/integration_tests/examples/material/test_banner.py

@@ -26,6 +26,17 @@ class Banner(DialogControl):
     Banners are displayed at the top of the screen, below a top app bar. They are
     persistent and non-modal, allowing the user to either ignore them or interact with
     them at any time.
+
+    ```python
+    banner = ft.Banner(
+        leading=ft.Icon(ft.Icons.INFO_OUTLINED, color=ft.Colors.PRIMARY),
+        content=ft.Text("Backup completed successfully."),
+        actions=[ft.TextButton("Dismiss")],
+        bgcolor=ft.Colors.SURFACE_CONTAINER_LOW,
+        open=True,
+    )
+    page.show_dialog(banner)
+    ```
     """
 
     content: StrOrControl