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>

tests/test_portal.py

@@ -129,11 +129,14 @@ class ManagerTests(unittest.IsolatedAsyncioTestCase):
             with self.assertRaises(ValueError): fresh.save('text.screen',{**saved,'settings':{'brightness':0}})
             self.assertEqual(path.read_bytes(),before)
             await fresh.sync_one('text.screen',saved)
-            self.assertEqual(fresh.ha.messages[0][1]['settings'],{k:v for k,v in settings.items() if k not in SETTINGS_BESIDE_BLOCK})
+            # The clock is the one of Settings -> Language & region (app 0.2.90), the rest what the screen kept.
+            self.assertEqual(fresh.ha.messages[0][1]['settings'],{**{k:v for k,v in settings.items() if k not in SETTINGS_BESIDE_BLOCK},
+                                                                   'clock_24h':fresh.region.clock_24h()})
             await fresh.sync_one('text.screen',saved)
             self.assertEqual(len(fresh.ha.messages),2)
             await fresh.sync_one('text.screen',saved,True)
-            self.assertEqual(fresh.ha.messages[2][1]['settings'],{k:v for k,v in settings.items() if k not in SETTINGS_BESIDE_BLOCK})
+            self.assertEqual(fresh.ha.messages[2][1]['settings'],{**{k:v for k,v in settings.items() if k not in SETTINGS_BESIDE_BLOCK},
+                                                                   'clock_24h':fresh.region.clock_24h()})
 
     async def test_reorder_aborts_old_batch(self):
         with tempfile.TemporaryDirectory() as temp: