fix(ios): don't mix recording with other apps' audio

[skrtdev]

Summary

The AVAudioSession options passed to setCategory(.playAndRecord, options:) in AudioRecorder.startRecording currently include .mixWithOthers:

let options: AVAudioSession.CategoryOptions = [.defaultToSpeaker, .allowBluetooth, .mixWithOthers]

.mixWithOthers tells AVAudioSession to let other audio apps (Spotify, Apple Music, Podcasts, system sounds, …) keep playing through the speaker for the duration of the recording. While that is the right behaviour for a playback session, for a recording session it has a nasty side effect: the device microphone picks up the speaker output and bleeds it straight into the recorded file. Every voice memo recorded while music is playing ends up being a mix of the user's voice and the music.

This is almost never what users want — the expected behaviour, and the behaviour every native voice-recording app on iOS implements, is that starting a recording interrupts other audio for the duration of the recording.

Change

Drop .mixWithOthers from the recorder's category options:

let options: AVAudioSession.CategoryOptions = [.defaultToSpeaker, .allowBluetooth]

Starting a recording now interrupts other apps' audio, the recording captures only what the microphone hears (user's voice + ambient), and the previously-playing app resumes when the recording session ends. No other code changes.

The player session (AudioPlayer.swift) is unrelated and not touched.

Test plan

• Play music in Spotify (or Apple Music / Podcasts).
• Start a recording with the library.
• Confirm: other audio stops, the recorded file contains only mic input (no music in the background).
• Stop the recording — other audio resumes (standard AVAudioSession behaviour).
• Record with no other audio playing — recording still works as before.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR adjusts the iOS recorder’s AVAudioSession configuration to prevent other apps’ audio from continuing during an active recording, avoiding speaker-to-mic bleed being captured in recorded files.

Changes:

• Removed .mixWithOthers from the recorder session’s AVAudioSession.CategoryOptions.
• Added an inline comment explaining why mixing is undesirable for recording sessions.

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