Helligkeitsregelung (LDR -> Stufe/Prozent) ergaenzt

- brightness.py: BrightnessController + CLI, portiert aus DoDimmen_V/main.h
  (gleitender Mittelwert, Hysterese). Schwellen 300/2500 aus altem Code,
  Prozente 5/15/50/100
- verallgemeinert auf 4 Stufen: 100% jetzt erreichbar (alter Code max 50%);
  neue obere Grenze HELL_MAX=3500 (anpassbar), Rest wie im Original
- run_display: --ldr bindet die Regelung in die Hauptschleife ein
  (sendet nur bei Stufenwechsel)
- test_brightness.py: Schwellen, Hysterese, Mittelung
- README dokumentiert die Regelung; .gitignore: Hardware/

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

test_brightness.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Tests fuer die Helligkeitsregelung (verallgemeinert aus DoDimmen_V).
+
+    python3 -m unittest -v test_brightness
+
+Grenzen: Mitten (300, 2500, 3500) mit Hysterese (30, 150, 150)
+ -> hoch bei 330 / 2650 / 3650, runter bei 270 / 2350 / 3350.
+"""
+
+import unittest
+
+import brightness
+from brightness import BrightnessController
+
+
+class TestStufen(unittest.TestCase):
+
+    def setUp(self):
+        self.c = BrightnessController()
+
+    def test_erststart_schaltet_von_0_hoch(self):
+        self.assertEqual(self.c._next_level(329, None), 0)
+        self.assertEqual(self.c._next_level(330, None), 1)
+        self.assertEqual(self.c._next_level(2649, None), 1)
+        self.assertEqual(self.c._next_level(2650, None), 2)
+        self.assertEqual(self.c._next_level(3649, None), 2)
+        self.assertEqual(self.c._next_level(3650, None), 3)   # 100 % erreichbar
+
+    def test_hysterese_von_stufe_1(self):
+        self.assertEqual(self.c._next_level(270, 1), 1)
+        self.assertEqual(self.c._next_level(269, 1), 0)
+        self.assertEqual(self.c._next_level(2649, 1), 1)
+        self.assertEqual(self.c._next_level(2650, 1), 2)
+
+    def test_hysterese_von_stufe_2(self):
+        self.assertEqual(self.c._next_level(2350, 2), 2)
+        self.assertEqual(self.c._next_level(2349, 2), 1)
+        self.assertEqual(self.c._next_level(3649, 2), 2)
+        self.assertEqual(self.c._next_level(3650, 2), 3)
+
+    def test_hysterese_von_stufe_3(self):
+        self.assertEqual(self.c._next_level(3350, 3), 3)
+        self.assertEqual(self.c._next_level(3349, 3), 2)
+
+    def test_prozente(self):
+        self.assertEqual(brightness.PERCENTS, (5, 15, 50, 100))
+
+
+class TestUpdate(unittest.TestCase):
+
+    def test_erste_aenderung_meldet_changed(self):
+        c = BrightnessController()
+        self.assertEqual(c.update(100), (0, 5, True))
+
+    def test_gleicher_wert_keine_aenderung(self):
+        c = BrightnessController()
+        c.update(100)
+        level, percent, changed = c.update(100)
+        self.assertFalse(changed)
+        self.assertEqual(percent, 5)
+
+    def test_dunkel_zu_hell_erreicht_100(self):
+        c = BrightnessController()
+        c.update(100)
+        level = percent = None
+        for _ in range(brightness.AVERAGE_WINDOW + 2):
+            level, percent, _ = c.update(4000)
+        self.assertEqual(level, 3)
+        self.assertEqual(percent, 100)
+
+    def test_gleitender_mittelwert_fenster(self):
+        c = BrightnessController()
+        for _ in range(20):
+            c.update(1000)
+        self.assertLessEqual(len(c._buf), brightness.AVERAGE_WINDOW)
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)