Pinned posts on profiles, and pinning from the card

A profile shows the posts the account pins above its posts (pinned=true: for an account elsewhere, what it features,
which PrivaPub now keeps); the persona pins and unpins its own public and unlisted posts from the card's menu, and
PrivaPub tells its followers. tests/e2e/Actions/PinTests.cs pins from the card and finds the post first on the profile;
the whole e2e suite passes against the reseeded village (122, 4 skipped).

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

CLAUDE.md

@@ -235,6 +235,8 @@ supplies:
   link, participants and status.
 - **Profiles and search** (`Pages/Profile.razor` at `/account/{id}`, `Pages/Search.razor` at `/search?q=`): a card's
   author and a notification's account open the profile in the app; "Open original" is the only way to the remote site.
+  A profile shows the posts the account pins above its posts (`pinned=true`: what an account elsewhere features); the
+  persona pins and unpins its own public and unlisted posts from the card's menu.
   An account that moved says where to (`Account.Moved`, which PrivaPub fills once the new account names the old one),
   linking the new account's profile.
   A card in a fixed-height flex column with `overflow-hidden` needs `flex-none`, or it collapses to nothing.