Dashboard route - loan applications over time

Create a `/dashboard/loan-applications-over-time` route to obtain data for the LineChart component including:
* labels
* number of applications
all for a given period (today, lastweek, lastmonth).

It should be accept GET requests and should have the following query params:
* period
* id
* token

Start at the backend route entry point and inspect how existing dashboard routes obtain and shape data. Implement the GET /dashboard/loan-applications-over-time behavior for the period, id, and token query parameters, returning labels and application counts for today, lastweek, and lastmonth; verify each requested period and parameter combination.

Written by the indexing model from the issue text.