Settings: change the login's password, or delete the login

A Login section in Settings changes the root's password (the current one
given) and deletes the whole login, every persona with it, after its
password and an explicit "I understand"; the client then signs out. Both
use PrivaPub's existing /clientapi/user routes.

The e2e signs up a login of its own, changes its password and deletes it,
checking each against PrivaPub's login. Signing in now waits for either
the feed or an enabled persona chooser, so a login with one persona (which
goes on by itself) and a new persona's empty feed both sign in.

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

CLAUDE.md

@@ -253,7 +253,9 @@ supplies:
 - **Interaction policies** (GoToSocial's): a reply or boost whose target's author must approve it shows so on its card
   (`privapub.approval`: pending, then nothing once approved, or rejected); one the policy shuts out is refused by
   PrivaPub (422) and shown as an error.
-- **Settings** (`Pages/Settings.razor`, `Components/Settings/`): the persona's profile (`ProfileEditor`:
+- **Settings** (`Pages/Settings.razor`, `Components/Settings/`): the login itself (`AccountEditor`: its password changed,
+  or the whole of it deleted, every persona with it, through `/clientapi/user/update/password` and `/clientapi/user/delete`;
+  the client then signs out), the persona's profile (`ProfileEditor`:
   `update_credentials` as multipart, its words as written from `Account.Source`, pictures, fields, locked, bot,
   discoverable, indexable and posting defaults; the composer starts a new post at its default visibility), its mutes,
   blocks and blocked servers (`MutesAndBlocks`), and `DataTransfer`: follows, lists, blocks, mutes, blocked servers