UX: clean up CLI setup and basic usage

[zmoog]

Motivation

The essential UX is a little chaotic. I want to design how to set up and run simple queries.

Change description

• Remove hard-coded values, so we can run queries using filters (year, period, different students, and more).
• Remove the 'Obiettivi' field; it looks like teachers don't use it.
• Partial Navigator refactoring to make it work across different years and periods; in the previous version it only worked well with the current year and period.
• Add --verbose option to print request and response details

Additional Notes

• Closes Clean up grade list command #11

Reviewer checklist

• PR address a single concern.
• PR title and description are appropriately filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.
• Docs are updated (at least the README.md, if needed).
• History is clean, commit messages are meaningful (see CONTRIBUTING.md) and are well-formatted.