Notation like Home Assistant, each screen in its own language, and the language in every build

From the end-to-end test on the bench boards and an independent review:
- Units spaced as Home Assistant does (54% / 54 % in German and French, 18°, 21.5 °C), in the firmware and the app.
- Grouping from five digits where the language does (1234 but 12.345 in Spanish, Polish, Portuguese): the layout
  message carries group_min and percent_space; an unknown number style no longer refuses a layout.
- Automatic follows Home Assistant's own language for the clock and numbers, also without a translation (Swedish:
  24 hours, 1 234,5; pt-BR: 1.234,5): regions.json from the CLDR for all 63 languages Home Assistant offers.
- 12-hour clock: the top bar says 3:48 PM, the clock card 3:48 (not 03:48), Last runs follow the clock.
- The climate setpoint font has the decimal comma; the value fonts have ², ³ and µ (m³ was a box).
- Weather days: at most three letters without the dot (mié, sáb, czw); the screen took three bytes.
- Texts fall back per key through the base language (pt-BR -> pt -> en) in the firmware and the app.
- Each screen gets the app's words in the language its firmware speaks; firmware from before the languages gets
  English and its own letters, not boxes.
- set_language re-reads what it writes (indentation, comments, quoted keys, CRLF, !include) and every build writes
  the language first; the 24-hour pin no longer hits a fresh install and waits for the old clock switches.
- Tests: region and notation, plural parity with the C++ rules, set_language edge cases, the pin, PUT /api/language.

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

screen_manager/app/header_bar.py

@@ -24,6 +24,8 @@ from i18n import TRANSLATIONS, screen_number, screen_t, t
 # The characters the screen's text fonts carry (the sublabel_big glyph list; tests/test_header_bar.py keeps them equal):
 # every letter European languages write with since app 0.2.90.
 GLYPHS = frozenset('<>—&@!,.?"%()+-_:°0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz/…·\'#*=;²³µ–ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿĄąĆćĘꣳŃńŚśŹźŻżČčĎďĚěŇňŘřŠšŤťŮůŽžĹ弾ŔŕŐőŰűĂăȘșȚțĐđĀāĒēĢģĪīĶķĻļŅņŪūĖėĮįŲųĞğİıŞşĊċĠġĦħŴŵŶŷĿŀŒœŸ„“”‘’«»‹›¿¡€£')
+# The letters of firmware from before the languages (0.2.75 and older), which gets what it can draw.
+LEGACY_GLYPHS = frozenset("<>—&@!,.?\"%()+-_:°0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyzäöüÄÖÜß/…·'#*=;²³µéèëêïîóôàáâçñúû–")
 TEXT_BYTES = 40
 # The months in English, the language of reference (tests/test_header_bar.py); a screen gets them in its own language
 # (short_date, app 0.2.90).
@@ -115,13 +117,14 @@ ALARM_CLASSES = frozenset(['battery', 'carbon_monoxide', 'gas', 'heat', 'lock',
 
 def clean_text(text):
     """Text the screen can draw: known glyphs, accents folded to the base letter, at most TEXT_BYTES."""
+    glyphs = LEGACY_GLYPHS if i18n.legacy_screen() else GLYPHS
     out = []
     for char in unicodedata.normalize('NFC', str(text)):
-        if char in GLYPHS:
+        if char in glyphs:
             out.append(char)
             continue
         base = unicodedata.normalize('NFKD', char)[0]
-        if base in GLYPHS:
+        if base in glyphs:
             out.append(base)
     return short(''.join(out).strip(), TEXT_BYTES)
 
@@ -142,10 +145,8 @@ def number_text(value, precision=None):
     return screen_number(text)
 
 def with_unit(text, unit):
-    """Home Assistant's spacing: "21.3 °C", "65%", "18°"."""
-    if not unit:
-        return text
-    return text + unit if unit in ('%', '°') else f'{text} {unit}'
+    """Home Assistant's spacing: "21.3 °C", "65%" ("65 %" in German and French), "18°"."""
+    return text + i18n.unit_suffix(unit)
 
 def precision_of(entry):
     options = ((entry or {}).get('options') or {}).get('sensor') or {}