Add padding at the bottom of the audio panel

[ahmedre]

On devices using the older navigation bar, the "apply" button is often
obscured in portrait mode. This fixes it by adding padding underneath
it.

[github-actions]

OLD: app-madani-debug.apk (signature: V1, V2)
NEW: app-madani-debug.apk (signature: V1, V2)

          │          compressed           │          uncompressed          
          ├───────────┬───────────┬───────┼───────────┬───────────┬────────
 APK      │ old       │ new       │ diff  │ old       │ new       │ diff   
──────────┼───────────┼───────────┼───────┼───────────┼───────────┼────────
      dex │  13.4 MiB │  13.4 MiB │   0 B │  34.3 MiB │  34.3 MiB │    0 B 
     arsc │   2.2 MiB │   2.2 MiB │   0 B │   2.2 MiB │   2.2 MiB │    0 B 
 manifest │   5.6 KiB │   5.6 KiB │   0 B │  27.1 KiB │  27.1 KiB │    0 B 
      res │   1.6 MiB │   1.6 MiB │ -66 B │   1.8 MiB │   1.8 MiB │ -192 B 
    asset │ 404.2 KiB │ 404.2 KiB │   0 B │ 678.6 KiB │ 678.6 KiB │    0 B 
    other │ 189.4 KiB │ 189.4 KiB │ -11 B │ 388.2 KiB │ 388.2 KiB │    0 B 
──────────┼───────────┼───────────┼───────┼───────────┼───────────┼────────
    total │  17.8 MiB │  17.8 MiB │ -77 B │  39.3 MiB │  39.3 MiB │ -192 B