Fix IMAP emails appearing empty: accept bytearray from aioimaplib literals

aioimaplib stores RFC822 literal data as bytearray in response.lines,
not bytes. The extraction loop checked isinstance(line, bytes) which
returns False for bytearray, silently dropping every email body and
causing all IMAP emails (T-Online, GMX, etc.) to appear empty.

Fix: accept (bytes, bytearray) and convert to bytes() immediately so
the rest of the pipeline is unaffected. Two new regression tests mirror
the real aioimaplib behaviour by passing bytearray as the literal.

Agent-Logs-Url: https://github.com/christianlouis/InboxConverge/sessions/341f5c82-70f8-438d-91ca-8e906a06c400

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

docs/TODO.md

@@ -4,6 +4,7 @@ Comprehensive task breakdown for repository improvements and production readines
 
 ## ✅ Recently Completed
 
+- [x] **IMAP: fix all emails appearing empty** — `aioimaplib` stores RFC822 literal data as `bytearray`, not `bytes`. The extraction loop was checking `isinstance(line, bytes)` which returns `False` for `bytearray`, so every email body was silently skipped. Fixed to accept both types and convert to `bytes`. Affected T-Online, GMX, and all IMAP accounts.
 - [x] **Security: upgrade fastapi/starlette and fix safety CI command** — Upgraded `fastapi` to `0.135.2` (pulls in `starlette>=1.0.0`) fixing 4 DoS CVEs in `starlette<=0.35.1`; replaced deprecated `safety check` with `safety scan`; added `.safety-policy.yml` to suppress unfixable `ecdsa` side-channel CVEs (maintainers won't fix).
 - [x] **IMAP RFC 3501 flag syntax & aioimaplib UID SEARCH fix**: `_fetch_imap_emails`
   now uses a plain `SEARCH UNSEEN` + `FETCH (UID)` to resolve sequence numbers to