Show a notification the sender updated, instead of the version it replaced

A client that updates a notification through replaces_id does not produce a
second onNotification: Quickshell writes the new content onto the Notification
object the shell is already holding. The card draws a snapshot copied out of
that object — deliberately, since a live QObject in a ListModel role becomes a
dangling pointer the moment the server destroys it — so the toast kept showing
the superseded text, and archived it to history when it left the screen. A
Slack thread that updates in place read as stuck.

Every property the card draws is now watched on the notification we hold, and
a change rewrites both the model row and the file the popup was persisted
under. The file name is that popup's identity, so the rewrite lands in place:
a shell restart restores the version last shown, and so does the copy that
reaches history.

The countdown starts over when the content changes. New text arriving a second
before the toast was due to expire deserves a full look, not the remainder of
the clock the text it replaced had nearly run through.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

shell/plugins/notifications/NotificationLogic.js

@@ -92,6 +92,17 @@ function snapshotOf(notification, timestamp) {
   }
 }
 
+// A client updating a notification through replaces_id keeps the identity of
+// the popup it took over: the file name is the timestamp and id the popup was
+// first persisted under, and the restore, replace and archive paths all key
+// off that name. Only what the card draws comes from the updated object.
+function replacementSnapshot(notification, originalId, timestamp) {
+  var updated = snapshotOf(notification, timestamp)
+  updated.id = originalId
+  updated.originalId = originalId
+  return updated
+}
+
 function historyEntry(value, normalUrgency) {
   var e = value || {}
   return {
@@ -265,6 +276,7 @@ if (typeof module !== "undefined") {
     execFromHints: execFromHints,
     shouldRenderCompactGlyph: shouldRenderCompactGlyph,
     snapshotOf: snapshotOf,
+    replacementSnapshot: replacementSnapshot,
     historyEntry: historyEntry,
     parseSettings: parseSettings,
     historyRows: historyRows,