Replace Qt Multimedia with a native audio abstraction

[i2h3]

Summary

Replaces the Qt Multimedia framework — used in exactly one place, to loop the incoming-call ringtone in CallNotificationDialog.qml — with NotificationSoundPlayer, a thin in-tree C++ class that wraps the OS-native audio APIs.

Platform	Backend	Loop semantics
macOS	AVAudioPlayer via Objective-C++	Native (numberOfLoops)
Windows	XAudio2 + inline RIFF/fmt/data parser	Native (XAUDIO2_BUFFER::LoopCount)
Linux	libcanberra (soft build dependency)	Per-play, dispatcher-driven

The QML diff is one removed import and one renamed element; ringSound.play() / ringSound.stop() call sites are unchanged. Native-loop backends play the whole sequence and signal finished once; per-play backends signal after each play and the dispatcher re-issues until the loop count is exhausted.

The dispatcher resolves qrc: / file: / plain-path sources, materialising QRC contents into the cache once with an atomic-rename and QTemporaryFile fallback for sandboxed runs.

Two dead Qt5Multimedia*.dll references in the NSIS template are deleted in the same commit (they could never resolve in the current Qt6 build).

Closes #9886

Test plan

• macOS — Build NextcloudDev locally; confirm the bundle no longer ships QtMultimedia.framework or qml/QtMultimedia/* (verified pre-merge: find Contents -iname '*Multimedia*' returns nothing).
• macOS — Trigger an incoming Talk call; ringtone plays, Decline stops, 60 s timeout stops, app exit while ringing stops cleanly.
• Windows — CI build green; trigger an incoming Talk call locally; same matrix.
• Linux — CI build green with and without libcanberra-dev; on a Pulse host and a Pipewire host: trigger an incoming Talk call; same matrix.
• Unit tests — NotificationSoundPlayerTest passes: covers resolveToFilesystemPath() (QRC extraction + idempotency, file://, plain path, empty, non-existent) and loop bookkeeping (per-play re-issues, native single-fire, stop-mid-sequence cancels).
• Audio device hotplug — Unplug the output device during playback on each platform; no crash or hang.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR removes the Qt Multimedia dependency used only for the incoming-call ringtone by introducing an in-tree NotificationSoundPlayer QML type backed by native OS audio APIs (AVAudioPlayer / XAudio2 / libcanberra-or-noop). This reduces packaging/deployment overhead while preserving the QML call sites (play()/stop()).

Changes:

• Replace SoundEffect usage in CallNotificationDialog.qml with NotificationSoundPlayer and drop the QtMultimedia import.
• Add NotificationSoundPlayer implementation + platform backends and register it for QML usage.
• Wire up build system (platform sources, native link flags, optional libcanberra) and add a unit test + remove dead NSIS Qt5Multimedia DLL lines.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
test/testnotificationsoundplayer.cpp	Adds unit tests for QRC resolution and loop bookkeeping.
test/CMakeLists.txt	Registers the new NotificationSoundPlayer test target.
src/gui/tray/CallNotificationDialog.qml	Switches ringtone element from QtMultimedia SoundEffect to NotificationSoundPlayer.
src/gui/owncloudgui.cpp	Registers NotificationSoundPlayer as a QML type.
src/gui/notificationsoundplayer.h	Declares the new QML-facing API and backend interface hooks.
src/gui/notificationsoundplayer.cpp	Implements dispatcher logic and QRC-to-filesystem extraction caching.
src/gui/notificationsoundplayer_p.h	Defines the backend interface and factory function contract.
src/gui/notificationsoundplayer_win.cpp	Windows XAudio2 backend + WAV parsing.
src/gui/notificationsoundplayer_mac.mm	macOS AVAudioPlayer backend.
src/gui/notificationsoundplayer_linux.cpp	Linux libcanberra backend + noop fallback.
src/gui/CMakeLists.txt	Adds sources and platform link/defines (AVFoundation/Foundation, xaudio2, optional libcanberra).
cmake/modules/NSIS.template.in	Removes stale Qt5Multimedia DLL references from the installer template.

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[sonarqubecloud]

Quality Gate failed

Failed conditions
64.4% Coverage on New Code (required ≥ 80%)
21 New Code Smells (required ≤ 0)

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[i2h3]

Oké, plans might change. Possibly the call notification feature will be removed entirely from the files client due to the Nextcloud Talk desktop client available since the feature release.