Add end-to-end tests for TLS RPT report ingestion and WebSocket event handling

- Implemented tests for ingesting TLS RPT reports from emails and ensuring they are stored correctly in the database.
- Added tests to verify that the same report can be ingested multiple times without duplication.
- Created tests for backfilling reports that were previously delivered to the inbox.
- Developed WebSocket event handling tests to ensure events are correctly routed to subscribers based on mailbox ownership.
- Included tests for the mail API to validate session handling, mailbox isolation, and error mapping.
- Ensured that the API rejects unauthorized requests and handles malformed JSON gracefully.

migrations/0008_add_reports_folder.up.sql

@@ -0,0 +1,17 @@
+-- Give every existing mailbox a Reports folder.
+--
+-- DMARC and TLS-RPT reports are delivered to the dmarc@ and tlsrpt@ aliases
+-- and are now parsed on arrival and filed here rather than into the inbox.
+-- Without the folder the delivery path falls back to INBOX, which is the noise
+-- this is meant to remove.
+--
+-- IMAP defines no special-use role for reports, so the folder is matched by
+-- name and special_use stays NULL.
+INSERT INTO folders (mailbox_id, name, special_use)
+SELECT m.id, 'Reports', NULL
+  FROM mailboxes m
+ WHERE NOT EXISTS (
+   SELECT 1 FROM folders f
+    WHERE f.mailbox_id = m.id
+      AND LOWER(f.name) = 'reports'
+ );