Let recurring giving links default to monthly instead of weekly #1492

Related Product
Giving

Is your feature request related to a problem? Please describe.
When using recurring=true_default to pre-select recurring giving, linking from our website to the giving form, the form defaults to a weekly frequency. For example:

https://yoursubdomain.churchcenter.com/giving?recurring=true_default

We'd like donors landing on this link to default to monthly instead, since that's the cadence we promote in our campaigns.

Describe the solution you'd like
Either of these would work for us:

1. Extend URL parameter support so the frequency itself can be set, e.g. recurring=true_default&frequency=monthly, or
2. Add a setting in the Giving form's admin settings to change the default recurring frequency, so weekly isn't the only option.

Describe alternatives you've considered
We haven't found a good alternative. The form simply defaults to weekly, so donors following our links may end up set to weekly giving even though we intended to promote monthly.

Additional context
This is related to a few earlier requests around frequency control on the giving form: #1250, #594, and #566. See the docs describing recurring=true_default: https://help.planningcenter.com/en/144372-link-to-your-donation-form-on-your-website.html#recurring-donation

I have..

• Reviewed the documentation found at https://developer.planning.center/docs
• Searched for previous issues asking for this feature request
• Removed all private information from this issue (credentials, tokens, emails, phone numbers, etc.)
• Reviewed my issue for completeness