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>

packages/core.yaml

@@ -679,7 +679,7 @@ font:
              'Ĺ','ĺ','Ľ','ľ','Ŕ','ŕ','Ő','ő','Ű','ű','Ă','ă','Ș','ș','Ț','ț','Đ','đ','Ā','ā','Ē','ē','Ģ','ģ',
              'Ī','ī','Ķ','ķ','Ļ','ļ','Ņ','ņ','Ū','ū','Ė','ė','Į','į','Ų','ų','Ğ','ğ','İ','ı','Ş','ş','Ċ','ċ',
              'Ġ','ġ','Ħ','ħ','Ŵ','ŵ','Ŷ','ŷ','Ŀ','ŀ','Œ','œ','Ÿ','„','“','”','‘','’','«','»','‹','›','¿','¡',
-             '€','£']
+             '€','£','²','³','µ']
 
   - file: "${FONT_DIR}/Roboto-500.ttf"
     id: watch_value
@@ -696,7 +696,7 @@ font:
              'Ĺ','ĺ','Ľ','ľ','Ŕ','ŕ','Ő','ő','Ű','ű','Ă','ă','Ș','ș','Ț','ț','Đ','đ','Ā','ā','Ē','ē','Ģ','ģ',
              'Ī','ī','Ķ','ķ','Ļ','ļ','Ņ','ņ','Ū','ū','Ė','ė','Į','į','Ų','ų','Ğ','ğ','İ','ı','Ş','ş','Ċ','ċ',
              'Ġ','ġ','Ħ','ħ','Ŵ','ŵ','Ŷ','ŷ','Ŀ','ŀ','Œ','œ','Ÿ','„','“','”','‘','’','«','»','‹','›','¿','¡',
-             '€','£']
+             '€','£','²','³','µ']
 
   # Clock card digits only; the date line reuses the tile title font.
   - file: "${FONT_DIR}/Roboto-500.ttf"
@@ -710,7 +710,7 @@ font:
     id: setpoint_digits
     size: ${FONT_SETPOINT_SIZE}
     bpp: 4
-    glyphs: ['-','.','°','0','1','2','3','4','5','6','7','8','9']
+    glyphs: ['-','.',',','°','0','1','2','3','4','5','6','7','8','9']
 
   - file: "${FONT_DIR}/Roboto-700.ttf"
     id: label
@@ -727,7 +727,7 @@ font:
              'Ĺ','ĺ','Ľ','ľ','Ŕ','ŕ','Ő','ő','Ű','ű','Ă','ă','Ș','ș','Ț','ț','Đ','đ','Ā','ā','Ē','ē','Ģ','ģ',
              'Ī','ī','Ķ','ķ','Ļ','ļ','Ņ','ņ','Ū','ū','Ė','ė','Į','į','Ų','ų','Ğ','ğ','İ','ı','Ş','ş','Ċ','ċ',
              'Ġ','ġ','Ħ','ħ','Ŵ','ŵ','Ŷ','ŷ','Ŀ','ŀ','Œ','œ','Ÿ','„','“','”','‘','’','«','»','‹','›','¿','¡',
-             '€','£']
+             '€','£','²','³','µ']
 
   - file: "${FONT_DIR}/Roboto-400.ttf"
     id: sublabel
@@ -744,7 +744,7 @@ font:
              'Ĺ','ĺ','Ľ','ľ','Ŕ','ŕ','Ő','ő','Ű','ű','Ă','ă','Ș','ș','Ț','ț','Đ','đ','Ā','ā','Ē','ē','Ģ','ģ',
              'Ī','ī','Ķ','ķ','Ļ','ļ','Ņ','ņ','Ū','ū','Ė','ė','Į','į','Ų','ų','Ğ','ğ','İ','ı','Ş','ş','Ċ','ċ',
              'Ġ','ġ','Ħ','ħ','Ŵ','ŵ','Ŷ','ŷ','Ŀ','ŀ','Œ','œ','Ÿ','„','“','”','‘','’','«','»','‹','›','¿','¡',
-             '€','£']
+             '€','£','²','³','µ']
 
   - file: "${FONT_DIR}/Roboto-400.ttf"
     id: sublabel_big