Create interface to ask which projects should sync to which google calendar

To automatically sync all the tasks of a specific course, e.g. a course of project:uni.sse....:

1. Find out how to sync all tasks of a specific (sub) project to a specific calendar


2. Create a simple interface that easily lets the user link projects and/or subprojects to specific calendars.


3. Ensure these are periodically synced.

The issue names no files, tests, or entry points, so first map how this installer integrates Taskwarrior hooks and where calendar synchronization would belong. Define the project-to-calendar interface and periodic-sync behavior, then add coverage demonstrating that configured projects sync to their selected calendars.

Written by the indexing model from the issue text.