fix: remove unused imports and bare f-string in test_format_connection_error.py (ruff F401/F541)

Agent-Logs-Url: https://github.com/christianlouis/InboxConverge/sessions/9fad41f9-3b9d-4b9b-8eb5-9d0291f6746a

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

backend/tests/unit/test_format_connection_error.py

@@ -13,12 +13,10 @@ import poplib
 import socket
 import ssl
 
-import pytest
 
 from app.services.mail_processor import (
     MailDebugRecorder,
     _format_connection_error,
-    _MAX_TRACE_BYTES,
     _MAX_TRACE_ENTRIES,
 )
 
@@ -239,7 +237,7 @@ class TestMailDebugRecorder:
         password = "s3cr3tP@ssw0rd!"
         rec = MailDebugRecorder()
         # Simulate the entries that production code actually records
-        rec.record("auth", f"Authenticated as user@example.com", {"elapsed_ms": 5})
+        rec.record("auth", "Authenticated as user@example.com", {"elapsed_ms": 5})
         rec.record("stat", "Mailbox has 3 messages", {"count": 3})
 
         import json