Journaling: capture at the queue, the built-in journal, retention

Phase 2 of the journaling spec.

- A copy of each message is taken in MessageWrapper::queue, after DLP and
  transport rules, for every enabled journal that takes it (direction and
  scope: everyone, or accounts, groups, domains, tenants). If the copy
  can't be taken the message isn't queued (temporary failure).
- The journal report: the envelope one field a line (sender, To, Cc, Bcc
  from the envelope, list members from their ORCPT, direction, held for
  review), then the queued message byte for byte as message/rfc822.
- The built-in journal under J in the inbuxa subspace: one chain per node
  whose links name each entry by SHA-256, so entries can expire out of
  chain order; purge leaves a marker, and verify catches an entry changed
  or removed early and a report that doesn't match.
- Retention per journal (30 to 3650 days); an entry keeps what it was
  written with. The daily maintenance purges what's due, keeping entries
  whose people a legal hold covers (deleted accounts a hold keeps too),
  and records the counts in the audit log.
- inbuxa:Journal get/set, audited by the request layer. Permissions
  680-683: administrators see and change journals; the Compliance Officer
  sees, searches and exports. Whoever changes journals may grant search and
  export without holding them, so officers can still be appointed.
- Catalog entries (inbuxa:Journal, source "journal"); spec as-built notes.

tests/src/system/journal.rs: validation, internal mail with a Bcc,
outgoing into two journals, incoming over LMTP, the report and its
original, tamper and early removal caught, hold-aware purge, retention
changes leave entries alone, disabled and removed journals take nothing.

crates/jmap/src/api/request.rs

@@ -285,6 +285,9 @@ impl RequestHandler for Server {
                                     SetResponseMethod::MailRule(set_response) => {
                                         set_response.update_created_ids(&mut response);
                                     }
+                                    SetResponseMethod::Journal(set_response) => {
+                                        set_response.update_created_ids(&mut response);
+                                    }
                                     SetResponseMethod::HeldMessage(set_response) => {
                                         set_response.update_created_ids(&mut response);
                                     }
@@ -512,6 +515,11 @@ impl RequestHandler for Server {
                     resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
                     crate::inbuxa::mail_rule::get(self, access_token, *req).await?.into()
                 }
+                // inbuxa: journaling
+                GetRequestMethod::Journal(mut req) => {
+                    resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
+                    crate::inbuxa::journal::get(self, access_token, *req).await?.into()
+                }
                 // inbuxa: the audit log (AU-9)
                 GetRequestMethod::AuditEvent(mut req) => {
                     resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
@@ -985,6 +993,22 @@ impl RequestHandler for Server {
                     .await?
                     .into()
                 }
+                SetRequestMethod::Journal(mut req) => {
+                    resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
+                    let reason = req.arguments.reason.clone();
+                    crate::inbuxa::audit::recorded(
+                        self,
+                        access_token,
+                        session,
+                        &method_name.obj.to_string(),
+                        None,
+                        reason,
+                        *req,
+                        |req| Box::pin(crate::inbuxa::journal::set(self, access_token, req)),
+                    )
+                    .await?
+                    .into()
+                }
                 SetRequestMethod::AuditExport(mut req) => {
                     resolve_account_id(&mut req.account_id, method_name.obj, access_token)?;
                     crate::inbuxa::audit_log::export_set(self, access_token, session, *req)