feat(activity): clearer cards, a Rejected view and Reopen for failed deliveries (#1618)

A batch of activity list changes from running it as an admin on my own
instance. They are separate commits that build on each other, so they
can be reviewed in order.

The cards read better. Every card gets a format pill (violet for audio,
orange for ebooks), the requester is named once, and finished cards say
how long a download took and how long ago it ended ("took 5m · 35m
ago"). A download that picked up work already under way shows a
Reattached pill.

Admins can tell what is automatic and what needs a person. A declined
request shows who declined it and when, anything with an `[auto]` note
reads "Declined automatically", and "Needs Review" becomes "No Match
Yet" with a line saying the search repeats on every sync.

There is a Rejected view next to History for admins, with Reopen on each
card and a way to hide the dead ones.

The part to read most carefully is the backend in `requests_service.py`
and `user_db.py`. An admin can now reopen a fulfilled request whose
download failed or was cancelled, and the reopen a failed download
triggers remembers which release failed, so the next search doesn't pick
it again.

I ran it on a scratch instance (when pulling them together to move from
my fork to upstream) as an admin with seeded requests and looked at the
pills, the durations, the wording and the Rejected view in a browser.
Reopening a fulfilled request I only exercised in the tests. The
frontend and Python suites, type check, ruff and basedpyright pass.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

<!-- coderabbit-ai-generated:v1 -->

## Summary by CodeRabbit

* **New Features**
* Admins can review rejected requests in a dedicated view, hide or
restore cards, and reopen requests.
* Fulfilled requests with failed or cancelled deliveries can be
reopened; the failed release is skipped in the next automatic search.
* Activity cards now show format badges, download timing, and when a
download resumes existing work.
* **Improvements**
* Activity views clarify automatic retries and actions, and show
reviewer names for admins.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

docs/users-and-requests.md

@@ -120,4 +120,14 @@ Admins can override the default ebook/audiobook modes and request rules for indi
 4. For fulfilled requests, delivery state is tracked through the download pipeline
 5. If delivery fails and the download cannot be retried, the request goes back to pending automatically so an admin can approve it again with a different release. An admin can also reopen a rejected request
 6. Users can cancel their own pending requests
-7. An admin can **reopen** a rejected request, from the Requests tab or from History. It goes back to pending with what the user originally asked for, and shows in the activity list again even if the user had dismissed it.
+7. An admin can **reopen** a rejected request, from the Requests tab or from History. It goes back to pending with what the user originally asked for, and shows in the activity list again even if the user had dismissed it. A fulfilled request whose download failed or was cancelled can be reopened the same way: it goes back to pending without its release, and the next automatic search skips the release that failed (an admin can still pick it by hand).
+
+An admin sees who declined a request and when on its card, with the admin note if one was given.
+
+### Rejected view (this fork)
+
+A button next to History opens **Rejected**: every rejected request, including ones cleared from the activity list, each with **Reopen**. A card can be hidden from this view, and **Show hidden (N)** in its header brings hidden ones back, so a request is never out of reach. Hiding here is separate from clearing a card in Activity.
+
+Every card shows the format as a coloured pill: **Audiobook** or **Ebook** on a request, or the file format (EPUB, M4B, MP3) once a release is chosen or downloaded. Audio is violet and ebooks are orange.
+
+Admin actions taken by scripts or automation carry an admin note starting `[auto]`, for example `[auto] Already in the library.`, so they can be told apart from decisions a person made.