Coming back to the feed shows it as it was left

Leaving the feed keeps it in Services/FeedMemory.cs (posts, waiting posts, cursors and scroll; ten minutes, for the same
feed of the same persona), so coming back from a thread or a profile shows it again at once, older pages included,
instead of reading it anew; newer posts come behind the "new" button and through the stream as before.
tests/e2e FeedMemoryTests goes to a thread and back without a new read of the home timeline; the whole suite passes
(123, 5 skipped).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

CLAUDE.md

@@ -289,7 +289,9 @@ supplies:
   are read on the first hover and kept for the session. PrivaPub's own host is the signed-in persona's account host,
   since the API may be reached under another name.
 - **The feed page** (`Pages/Index.razor`): `FeedTabs`, `Content` (the card, which does its own actions), `Composer`,
-  `GlobePanel`. Older pages load as the end comes near (`wwwroot/js/feed.js`). Newer ones come through PrivaPub's
+  `GlobePanel`. Leaving it keeps the feed in `Services/FeedMemory.cs` (its posts, waiting posts, cursors and scroll,
+  ten minutes, for the same feed of the same persona), so coming back from a thread or a profile shows it again at once
+  without reading it anew. Older pages load as the end comes near (`wwwroot/js/feed.js`). Newer ones come through PrivaPub's
   streaming API (`Services/StreamingService.cs`: one WebSocket, the persona's token as its protocol, never in a URL)
   for home, lists, local, federated, hashtags and notifications, and wait behind a "new" button; a deletion or an edit
   it tells applies at once. Other feeds, and any feed while the stream is down, are polled every 45 s while visible.