Add Dark mode for a screen beside the bed, with every colour in one table (0.2.63)

Dark mode is a new switch under Brightness on the screen's settings page, in
the Screen settings of ESP Screens and as switch.<screen>_dark_mode in Home
Assistant, so an automation can turn it on at bedtime. The screen changes
look at once, open cards and an alert included, and keeps it after a
restart. The design stays the same: a black page, graphite cards with a
hairline, soft white text, Home Assistant's state colours where they tell
something, and pastel card colours as deeper versions of themselves.

Every colour the firmware chooses now lives in components/smart_display/
theme.h: roles with a light and a dark value, the named card colours and
Home Assistant's state colours. The board profiles give widgets colourless
shared styles that theme.h fills, so a change of look refills those styles
and draws again what code painted by state. The light look is unchanged
apart from merges below one panel step. Dark mode costs 440 bytes of static
RAM on the CYD, and the LVGL tree of the host build is 416 bytes smaller; tests
keep colours out of every other file.

Comparing a screen that switched looks with one that booted in it also
found two older bugs, now fixed: a settings switch that was on showed its
knob at the left whenever its page was drawn, and the sun card's sunlit
area turned orange after a palette change. Firmware 0.2.54.

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

tests/test_off_look.py

@@ -13,6 +13,7 @@ import header_bar  # noqa: E402
 import tile_icons  # noqa: E402
 
 TILES = (ROOT / 'components/smart_display/runtime_tiles.h').read_text()
+THEME = (ROOT / 'components/smart_display/theme.h').read_text()
 
 
 class OffLook(unittest.TestCase):
@@ -23,7 +24,9 @@ class OffLook(unittest.TestCase):
 
     def test_the_screen_crosses_out_its_own_bulb_and_greys_what_is_off(self):
         self.assertIn('if (d == "light" && tile.state == "off") return "\\U000F0E4F";', TILES)
-        self.assertIn('(t.is_switch()||d=="light"||d=="binary_sensor"||d=="person"||d=="timer") && !on ? 0x9E9E9E : accent', TILES)
+        self.assertIn('(t.is_switch()||d=="light"||d=="binary_sensor"||d=="person"||d=="timer") && !on ? theme::STATE_OFF : accent', TILES)
+        self.assertIn('constexpr uint32_t STATE_OFF = ha::GREY;', THEME)
+        self.assertIn('constexpr uint32_t GREY = 0x9E9E9E;', THEME)
 
     def test_the_top_bar_does_the_same(self):
         light = lambda state, **attrs: {'state': state, 'attributes': attrs}