fix(core,fuse,gui): a photo upload the SDK refuses no longer says offline

Every SDK error that was not an API reply was classified as Offline.
Only a transport failure is. An upload on an account without a photo
library fails in the SDK before any request, and the app said "You're
offline" while every other call worked (issue #38).

Classify by variant: Transport is Offline, InvalidOperation is Invalid,
Serialization is Remote, Crypto and KeysLocked are Internal. The daemon
logs a failed photo upload, and the Photos page greys out Upload when
the account has no photo library.

docs/BUGS.md B205.

docs/CHANGELOG.md

@@ -11,6 +11,12 @@ scratch (user data in `staging/` and `recovery/` is never touched by this).
 
 ## [Unreleased]
 
+### Fixed
+- **A failed photo upload said "You're offline" while everything else worked.** Only a failed
+  connection now reads as offline. Other failures show what went wrong, and Upload is greyed out
+  on an account without a photo library.
+  ([#38](https://github.com/narrrl/proton-drive-linux/issues/38))
+
 ## [3.2.1] — 2026-10-11
 
 Schema: **42**, unchanged.