Fix INMP441 silent meter: stereo I2S slots and DC removal.

ESP32 left/right naming often mismatches L/R=GND, and DC bias made dB look stuck.

Co-authored-by: Cursor <cursoragent@cursor.com>

firmware/cyd_28r/VERSION.txt

@@ -1,5 +1,5 @@
 name: CYD inmp441test (cyd_28r)
-git: unknown
+git: 59b85fb
 date: 2026-10-27
 board: ESP32-2432S028R (ILI9341)
 inmp441: WS=GPIO22 SCK=GPIO27 SD=GPIO35
@@ -13,5 +13,5 @@ offsets:
 sha256:
   bootloader.bin  3D234A7471F67B013686DABD4DEE7C1FA915C9928463616A94BC9297ACF1ABF8
   boot_app0.bin   F94C5D786A7A8FAB06AC5D10E33BF37711A6697636DC037559EA19CC410A17F0
-  firmware.bin    0CA34A45377F5EDCAB501E510F97B28A9B7FCEB34D6C65F0B71691C784C41999
+  firmware.bin    81B26992192E72F77396E0B71782C145EFE106F996D9E432F1551F5182CC6710
   partitions.bin  0A8B5720E7B77FF11F1462458C3A509DEE79224E5279898F26D6A2E3AE0517B7