fix: update test to use quality_score for quality ordering

Closes #139, closes #138

The test assumed bits_per_channel correlates with quality, but q4_0 (4.0 bits)
has lower quality than turbo2 (1.5 bits). Updated test to use explicit
quality_score field instead.

tests/test_quant_selector.py

@@ -22,7 +22,10 @@ class TestQuantLevels:
     def test_levels_ordered_by_quality(self):
         """Levels should be ordered from best quality to most aggressive."""
         for i in range(len(QUANT_LEVELS) - 1):
-            assert QUANT_LEVELS[i].bits_per_channel > QUANT_LEVELS[i + 1].bits_per_channel
+            # Use quality_score for explicit quality ordering
+            # (bits_per_channel doesn't always correlate with quality:
+            #  q4_0 has 4.0 bits but lower quality than turbo2 with 1.5 bits)
+            assert QUANT_LEVELS[i].quality_score > QUANT_LEVELS[i + 1].quality_score
 
     def test_all_levels_have_required_fields(self):
         for level in QUANT_LEVELS:
@@ -32,6 +35,7 @@ class TestQuantLevels:
             assert level.quality_label
             assert level.layer_adaptive >= 0
             assert level.kv_type
+            assert level.quality_score > 0
 
 
 class TestKVEstimate: