Mail is content: a state's mail: and the invite mail, published for gdo

`mail: { to, subject, body }` on a state in aggregates.yaml sends when a
record enters that state, `to: submitter` or one address, templates
over the record's fields plus {site}, {chain}, {email}. An invite mails
its one-time link built in, reworded by `mail.invite` in site.yaml,
which also carries the sender (`mail.from`, `mail.reply_to`); without
it a site sends nothing and says so in the log. Portal renders the
text and an HTML alternative and publishes one message per state
change on portal.mail.send in the WORMHOLE stream, id <bucket>:<record>
:<state> so a retried transition sends once; uhhm/gdo holds the
durable consumer and talks SMTP. The lint requires a required email
field on every form recording into a bucket that mails the submitter.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L4jrCgLiKKHAEFuZUJjckH

src/answers.rs

@@ -268,6 +268,7 @@ async fn apply_transition(
         .put(&item.item_id, data.into())
         .await
         .map_err(|e| ServerFnError::new(e.to_string()))?;
+    crate::mail::on_state(state, bucket, &item.item_id, &item.to, &answer.responses).await;
 
     // The decision extends the DAG as a child of the answer's own
     // submission hash, published like any other answer.
@@ -378,6 +379,7 @@ pub async fn self_transition_answer(
         .put(&item_id, data.into())
         .await
         .map_err(|e| ServerFnError::new(e.to_string()))?;
+    crate::mail::on_state(&state, &self_transition.bucket, &item_id, &self_transition.to, &answer.responses).await;
 
     let parent_hashes = vec![item_id.clone()];
     let chain_hash = hash_node(&question_id, &parent_hashes, &decision_payload_for_event, decided_ms);