add a button to clear out finished share links

The dashboard listed every share ever made, including ones revoked or expired
months ago, and nothing ever pruned them. There is now a "Clean up finished links"
button next to Refresh that runs a normal cleanup pass and then drops the records
that are done with, reporting how many went.

Only revoked, expired and failed records are removed. A link that can still be
used is left alone, including a spent one-use link whose guest is still watching
until it expires, since that record is Redeemed rather than finished.

Folded into 1.0.3.0 rather than shipped as 1.0.3.1: the ceiling fix and this are
going out as one replacement of that version.

Jellyfin.Plugin.ShareLinks/meta.json

@@ -1,12 +1,12 @@
 {
   "guid": "68540b76-ee74-436d-85ff-2abc884bbea6",
   "name": "ShareLinks",
-  "version": "1.0.3.1",
+  "version": "1.0.3.0",
   "targetAbi": "10.11.0.0",
   "framework": "net9.0",
   "owner": "Franciskid",
   "overview": "Secure expiring guest-share links for Jellyfin items.",
   "description": "Adds secure, expiring share links for Jellyfin items with JSON-backed storage, token hashing, and cleanup scaffolding.",
   "category": "General",
-  "timestamp": "2026-07-26T20:00:00.0000000Z"
+  "timestamp": "2026-07-26T20:15:00.0000000Z"
 }