Allow customized chore cadences

[kronosapiens]

Currently, all workspaces use a monthly chore cadence. Investigate allowing the customization of cadences.

This could be most simply implemented via a slash command which invokes a modal to collect all the relevant configuration information. This information might include:

• The unit of a chores cycle (days, weeks, months, or years)
• The number of units in a chores cycle
• The starting date of a chores cycle

This information can uniquely establish a chores cycle. All chores done before the start date should be excluded. Updating the chores cycle overwrites any existing cycle information. Start date cannot be set in the past.