Deep-review round 4, the "one report per failure" contract round 3 introduced.
- `req` marked gateway (502/503/504) and network failures "already reported" because they raise
the connection notice. But that notice is about connectivity and removes itself on the very next
answer — which every caller's own resync refetch fetches at once — so a delete that hit a
keepalive reset flashed the notice and was then reported nowhere, the list still there. Only the
durable reports (the error dialog, the 401 sign-out) count now; the caller says the action failed.
- A connection notice the user closed swallowed every later one for the rest of the visit; it is
raised again.
- `req` and `uploadReq` share one failure policy (`reportFailure`). The upload copy had drifted: a
502 opened the blocking "Server error (502)" dialog and cleared a notice that was still true.
- A taken Plex collection name is a structured 409, localized, and the create/rename calls are
quiet: it was an English dialog plus a Hungarian toast. `notifyCollectionEditError` is gone.
- The mutation onErrors that toasted unconditionally after a non-quiet request (invite approve /
deny / add, demo whitelist, audit clear, scheduler, share, full history, edit, config tests, tag
attach) go through `notifyActionError`; the playlist delete's hand-rolled copy of it too (it takes
a level now). The user role / suspend / delete actions had no onError at all: a user deleted in
another tab failed silently and stayed listed — now said, and the list refetched.