Surface unfinished appointments so dropped items get caught

[phinze]

📚 Stacked on #2185. This targets the appointment-hold-expiry-fixes branch, so review/merge #2185 first; GitHub will retarget this to main once that lands.

What it does

Adds an Unfinished Appointments report (under Reports) and a banner on the Appointments page that links to it. Both surface appointments where staff pulled the items, never marked the appointment complete, and at least one held item never got checked out. Each row can be resolved in place with a Mark complete button, and links to the appointment, member, and items for anything that needs a closer look.

"Unfinished" means: pulled, never completed, from the last 30 days, and still holding at least one item that's neither checked out nor explicitly ended (cancelled or retired). Today's and future appointments are never included, so the normal pickup flow doesn't show up here.

Why it is important

This is the third piece of the "items wandering off member accounts" story that staff have been reporting. The thread started from a real incident: an item showed as checked out to a member, but there was no loan behind it. Digging in, what actually happened was an appointment got pulled (items physically came off the shelf), some items went home and got checked out, one didn't, and the appointment was never closed. Nothing surfaces that half-finished state, so it just scrolls off that day's schedule and is forgotten. Weeks later, when someone goes looking for the item, the system looks like it's lying.

#2180 and #2181 (the stacked-under PR) stop the appointment page from mislabeling timed-out holds and stop holds from expiring mid-appointment. But neither makes the dangling appointments visible, which is what lets them rot. This adds the daily worklist: a short, recent list of appointments that need a human to close the loop, with the resolve action right there so it isn't a multi-click safari.

The 30-day window came out of checking prod before shipping. The naive "all pulled-but-never-completed appointments with an un-checked-out item" query returns ~330 rows stretching back over a year, and 70% of those items have been loaned to someone else in just the last 90 days (35% are checked out right now). In other words the old rows are stale records, not lost tools, and dumping 330 of them on staff would train everyone to ignore the list. Scoped to 30 days it's ~50 actionable rows. The report copy says so out loud, so the scoping isn't a silent surprise.

UI Change Screenshot

Banner on the Appointments page:

Unfinished Appointments report with the Mark complete action:

Implementation notes

A few decisions worth a look in review:

• Scope excludes already-ended holds (loan_id nil and ended_at nil), so holds that were cancelled/retired (or hit the create_loan_from_hold silently ends a hold when the loan fails to save #2183 save-failure bug) don't show as unfinished. Expired-but-not-ended holds still surface, since that's exactly the signal we want.
• The 30-day window is a constant (Appointment::UNFINISHED_WINDOW), and the report/banner copy is derived from it so they can't drift. The pre-existing backlog is intentionally out of scope here; it's a separate "bulk-complete old pulled appointments" decision we can make deliberately later.
• Inline resolve posts to a complete action that sets completed_at and 303-redirects back to the report, so it plays nicely with Turbo and the row just drops off. Reversible from the appointment page.

Fixes #2182