Show a spinner while a screen starts and while a camera loads, bring a camera's first picture sooner, and round the alert's camera picture (0.2.87)

Starting screen: until the first layout, render() keeps the status text
("Connecting to Home Assistant", "Waiting for ESP Screens") and a spinner
as one block in the middle of the page; the first layout deletes both.
The room label stays empty meanwhile, and ROOM_NAME defaults to "".

Camera: the full screen shows a spinner instead of "Loading image". The
screen asks when the camera opens and loads a link as soon as it comes
(camera_load, never under a finger) instead of waiting for the 250 ms
tick twice, and online_image reads 16 KB per loop instead of 4 KB. On the
bench Guition with the EZVIZ camera: cold 5.8 -> 4.55 s, warm 3.4 -> 2.06 s.

Alert picture: the image takes the frame's radius (18, the alert card's);
LVGL's software renderer clips it row by row, without a layer.

One spinner_create() makes the busy sheet's, the starting screen's and the
camera's spinner; theme role CAMERA_TRACK colours the camera's ring. The
README gets a row of camera pictures; docs/CAMERA.md, RELEASING.md and
TEST_RESULTS_0287.md describe the measurements.

Checked with tools/check.sh (473 Python tests, 19/19 C++, editor) and
--firmware: CYD 1,678,816 B (91.5 %, +1,312 B), Guition 2,055,280 B
(25.3 %). Host renders of both boards in both looks; four OTA builds on
the bench Guition Wallbox, which runs this firmware.

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

tests/test_header_bar.py

@@ -221,9 +221,24 @@ class ParityTests(unittest.TestCase):
             self.assertIn('runtime_tiles::time_label = id(lbl_time);', text, name)
             refresh = text.split('  - id: ui_refresh', 1)[1].split('return;', 1)[0]
             self.assertNotIn('lbl_time', refresh, name)
-        self.assertIn('render_header();', TILES.split('inline void render(lv_obj_t *room) {', 1)[1].split('\n', 5)[4])
+        self.assertIn('render_header();', TILES.split('inline void render(lv_obj_t *room) {', 1)[1].split('\n}', 1)[0])
         self.assertLessEqual(HEADER_MIN_FIRMWARE, tuple(int(p) for p in FIRMWARE_VERSION.split('.')))
 
+    def test_a_starting_screen_says_what_it_waits_for_in_the_middle(self):
+        # Firmware 0.2.73+: until the first layout the text and a spinner stand in the middle and the name stays empty;
+        # the first layout deletes them, so no spinner turns behind the tiles.
+        render = TILES.split('inline void render(lv_obj_t *room) {', 1)[1].split('\n}', 1)[0]
+        self.assertIn('if (!model.configured) boot_status(lv_obj_get_parent(room), !ha_connected() ? '
+                      '"Connecting to Home Assistant" : "Waiting for ESP Screens");', render)
+        self.assertIn('else if (boot_panel) { lv_obj_delete(boot_panel);', render)
+        self.assertIn('label(room, !model.configured ? "" :', render)
+        boot = TILES.split('inline void boot_status(', 1)[1].split('\n}', 1)[0]
+        self.assertIn('boot_spinner = spinner_create(boot_panel,', boot)
+        # Under the tiles, the cards and an alert, in the name's place.
+        self.assertIn('lv_obj_move_to_index(boot_panel, lv_obj_get_index(room_label));', boot)
+        for name in PROFILES:
+            self.assertNotIn('Choose tiles in HA', profiles.text(name), name)
+
     def test_second_hand_runs_only_while_the_screen_is_awake(self):
         for name in PROFILES:
             text = profiles.text(name)