Accounts the content mandates, a seed for the first person, and edits suggested by who is responsible

Every person a page names as responsible gets a Kanidm account at start
if they have none, and a mail saying they are listed as responsible for
asking that question, with the link to sign in; RESPONSIBLE_GROUP puts
them in one group. SEED_ADMIN_EMAIL invites the first person into the
most privileged group - the one whose desk may invite into the most -
once. Signed in, a responsible person may suggest a change to their
own pages; checked on the server, kept, published, and mailed to the
site's inbox.

Fixes an invite of someone new on a Kanidm with only the onboarding
account: the person is created with their address in one call, since
idm_people_on_boarding may create but not modify (it answered 403).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

src/auth.rs

@@ -14,6 +14,10 @@ pub struct User {
     /// live, so a group change only takes effect on the next login.
     #[serde(default)]
     pub groups: Vec<String>,
+    /// The address Kanidm holds for them (the `email` claim), so a page
+    /// can know it is talking to the person it names as responsible.
+    #[serde(default)]
+    pub email: Option<String>,
 }
 
 pub const SESSION_USER_KEY: &str = "user";