Show who is at the door: camera images on the Guition (0.2.66)

An alert from esp_screens_show_alert takes a `camera` (a camera.* or image.* entity): a Guition with firmware
0.2.57 shows that moment's picture across the top of the card, and a tap opens the camera full screen. A camera
or image tile opens the same full-screen view, refreshed every four seconds at a steady pace.

ESP Screen Manager fetches the snapshot with its own access, sizes it for the screen and serves a 24-bit BMP
under a random, short-lived link on port 8098; the screen loads it with ESPHome's online_image and holds no
Home Assistant token. BMP because ESPHome decodes it per chunk, where a full-screen JPEG held the loop 0.6 s.
The CYD keeps its alerts without the picture and gets no camera tiles.

The Guition also builds with ESPHome 2026.8+ again: backlight_fade.h derived from ESPHome's LEDC output, which
2026.8 made final, so the backlight now dims through ESPHome's own light transition.

Tested on the bench boards and a local add-on on the Home Assistant Yellow; docs/TEST_RESULTS_0266.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_wake_sleep.py

@@ -84,9 +84,9 @@ class Profiles(unittest.TestCase):
             self.assertIn('- script.execute: back_to_page_1_when_due', interval, name)
             self.assertNotIn('auto_home', interval, f'{name}: one copy of the rule')
             self.assertEqual(len(re.findall(r'script\.execute: back_to_page_1_when_due', text)), 2, name)
-            # Written by the boot, the three touchscreen triggers, Home Assistant opening the settings page and the
-            # UI self test only; Wake, an alert ending and Auto standby restart the standby time alone.
-            self.assertEqual(len(re.findall(r'id\(last_use_ms\) = millis\(\);', text)), 6, name)
+            # Written by the boot, the three touchscreen triggers, Home Assistant opening the settings page (and, on the
+            # Guition, a camera) and the UI self test only; Wake, an alert ending and Auto standby restart the standby time alone.
+            self.assertEqual(len(re.findall(r'id\(last_use_ms\) = millis\(\);', text)), 7 if 'preview_camera' in text else 6, name)
             touch = section(text, 'touchscreen')
             for trigger in ('on_touch', 'on_update', 'on_release'):
                 body = re.search(rf'^  {trigger}:\n(.*?)(?=^  [a-z_]+:|\Z)', touch, re.M | re.S)[1]