Auto Upload: JPEG conversion uses compressionQuality 1.0, tripling file size (regression in #4223)

[naelfe]

Steps to reproduce

1. iOS Camera set to "High Efficiency" (HEIC), 24 MP (never manually changed in iOS)
2. Enable Auto Upload with compatibility mode (HEIC -> JPEG)
3. Compare the uploaded JPEG size before and after app version 34.1.2

Actual behaviour

Same source photo (5712x4284, ~7 MB HEIC) now produces a ~23 MB JPEG.
Before 34.1.2 the same kind of photo produced ~8 MB. (first observed at around 2026-08-26)

Expected behaviour

Converted JPEGs should stay in a reasonable size range. Quality 0.8-0.9 is
visually indistinguishable here and produces roughly a third of the filesize.

Cause

In iOSClient/Utility/NCCameraRoll.swift, commit 82634b5 (PR #4223)
added options: [compressionQuality: 1.0] to the jpegRepresentation call.
Previously no options were passed and Core Image's default was used.

Quality 1.0 forces the encoder into a very inefficient mode, and since the
source is an already-compressed HEIC, its compression artifacts get encoded
into the JPEG as well. Apple confirms this behaviour and recommends ~0.8:
https://developer.apple.com/forums/thread/793946

Suggestion

Lower the constant to 0.85, or expose it as a setting next to the existing
compatibility-mode toggle.

Environment

• iPhone 16, iOS 26.6.1
• Nextcloud iOS app: 34.1.4.1
• Nextcloud server: 34.0.3

Hope this helps :-)