tec: Associate time spent with corresponding message

[marien-probesys]

Related issue(s)

#612

How to test manually

1. Answer with a message containing the string #oncall and add time spent
2. In the database (./docker/bin/psql bileto), run:

SELECT u.email, SUM(ts.real_time)
FROM time_spent ts, users u, message m
WHERE ts.created_by_id = u.id
AND ts.message_id = m.id
AND m.content LIKE '%#oncall%'
AND ts.created_at >= '2024-11-01'
AND ts.created_at < '2024-12-01'
GROUP BY u.email;

3. verify it shows the time spent

Checklist

• Code is manually tested
• Permissions / authorizations are verified
• New data can be imported (see Import missing data #751)
• Interface works on both mobiles and big screens
• Interface works in both light and dark modes
• Interface works on both Firefox and Chrome
• Accessibility has been tested
• Translations are synchronized
• Tests are up to date
• Copyright notices are up to date
• Documentation is up to date
• Pull request has been reviewed and approved