Introduce timezones.

Having timezones will help in adding jobs on channels that don't actually run on the local timezone.
This can be done in three steps:
1. Add default timezone for each channel.
2. Ability to specify timezones while adding jobs.
3. Make the scheduler use the provided timezone.

Look for channel configuration and job scheduling code. The issue outlines three steps: adding a default timezone to channels, allowing timezone specification when adding jobs, and making the scheduler respect the timezone. Start by examining how channels are defined and where jobs are created. Check existing datetime handling to understand the current time assumptions. 'Done' means jobs can be scheduled in non-local timezones.

Scritto dal modello di indicizzazione a partire dal testo della issue.