Simplify air purifier support by reusing existing helpers

Rewires /mode/vs/0's packed-options parsing (display_light/operating_mode/
blooming_level) onto laundry.py's existing option_value/replace_in_options/
bool_option_exists/bool_option_value instead of hand-rolled reimplementations,
hoists the duplicated int-conversion helper into common.py (shared by
range_hood.py too), collapses the five near-identical AIR_QUALITY sensors
into a table-driven loop, extracts the /consumable/vs/0 item lookup into a
named helper, and moves the humidity ignore list into capabilities/
air_purifier.py's own COVERAGE list to match the airconditioner/range_hood
convention of keeping by_type files as pure composition.

No behavior change; golden state keys and all existing tests are unaffected.

tests/test_air_purifier_capabilities.py

@@ -72,7 +72,8 @@ def test_diagnosis_reuses_dishwasher_capability():
 
 def test_light_switch_write_contract():
     """The display-light switch RMW-replaces only the 'Light_*' entry in the
-    packed /mode/vs/0 options list, preserving the other flags."""
+    packed /mode/vs/0 options list (via laundry.replace_in_options), leaving
+    the other flags and the list order untouched."""
     desc = next(e for e in air_purifier.MODE.entities if e.key == 'display_light')
     rep = {'x.com.samsung.da.options': [
         'Comode_Off', 'Blooming_0', 'Light_On', 'OptionCode_60282',
@@ -81,7 +82,7 @@ def test_light_switch_write_contract():
     assert desc.write_fn('Off', rep) == (
         ['mode', 'vs', '0'],
         {'x.com.samsung.da.options': [
-            'Comode_Off', 'Blooming_0', 'OptionCode_60282', 'Light_Off',
+            'Comode_Off', 'Blooming_0', 'Light_Off', 'OptionCode_60282',
         ]},
     )