test(#134): mail.py Coverage 88.2% → 100%

- TestSendSync.test_raises_when_smtp_not_configured: leerer host/user
  fuehrt zu RuntimeError
- TestSendSync.test_calls_smtp_ssl_with_settings: smtplib.SMTP_SSL wird
  mit host/port instanziiert, login + send_message aufgerufen
- TestSendMailAsync.test_runs_send_sync_in_executor: send_mail()
  delegiert per loop.run_in_executor an _send_sync

tests/test_mail.py

@@ -352,3 +352,63 @@ class TestRunDailyDigest:
 
         assert result["failed"] == 1
         assert result["sent"] == 0
+
+
+# ─── SMTP-Send-Path Coverage (#134 Backfill) ─────────────────────────────────
+
+
+class TestSendSync:
+    def test_raises_when_smtp_not_configured(self, monkeypatch):
+        """Wenn settings.smtp_host oder smtp_user leer ist, RuntimeError."""
+        from app import mail as mail_mod
+        from app.config import settings
+        monkeypatch.setattr(settings, "smtp_host", "")
+        monkeypatch.setattr(settings, "smtp_user", "user@example.com")
+        with pytest.raises(RuntimeError, match="SMTP nicht konfiguriert"):
+            mail_mod._send_sync("to@example.com", "subj", "text", "<p>html</p>")
+
+    def test_calls_smtp_ssl_with_settings(self, monkeypatch):
+        """Bei vollstaendiger Konfig wird smtplib.SMTP_SSL aufgerufen, login
+        und send_message getriggert."""
+        from unittest.mock import MagicMock
+        from app import mail as mail_mod
+        from app.config import settings
+        monkeypatch.setattr(settings, "smtp_host", "smtp.test")
+        monkeypatch.setattr(settings, "smtp_port", 465)
+        monkeypatch.setattr(settings, "smtp_user", "user@test")
+        monkeypatch.setattr(settings, "smtp_password", "pw")
+        monkeypatch.setattr(settings, "smtp_from_email", "noreply@test")
+        monkeypatch.setattr(settings, "smtp_from_name", "Test")
+
+        ssl_mock = MagicMock()
+        server_mock = MagicMock()
+        ssl_mock.return_value.__enter__.return_value = server_mock
+        ssl_mock.return_value.__exit__.return_value = False
+        monkeypatch.setattr(mail_mod.smtplib, "SMTP_SSL", ssl_mock)
+
+        mail_mod._send_sync("to@test", "subj", "Plain", "<p>HTML</p>")
+
+        # SMTP_SSL wurde aufgerufen mit host + port
+        ssl_mock.assert_called_once()
+        args, kwargs = ssl_mock.call_args
+        assert args[0] == "smtp.test"
+        assert args[1] == 465
+        # Login + send wurden aufgerufen
+        server_mock.login.assert_called_once_with("user@test", "pw")
+        server_mock.send_message.assert_called_once()
+
+
+class TestSendMailAsync:
+    def test_runs_send_sync_in_executor(self, monkeypatch):
+        """send_mail (async) delegiert an _send_sync via Thread-Executor."""
+        import asyncio
+        from unittest.mock import MagicMock
+        from app import mail as mail_mod
+
+        called: list[tuple] = []
+        def fake_sync(to, subj, text, html):
+            called.append((to, subj, text, html))
+
+        monkeypatch.setattr(mail_mod, "_send_sync", fake_sync)
+        asyncio.run(mail_mod.send_mail("to@test", "subj", "text", "<p>html</p>"))
+        assert called == [("to@test", "subj", "text", "<p>html</p>")]