GET /license_info: Flow PT REST endpoint

How many seats the site has and how many are spoken for. The only call that answers it.

Params

part	value
(none)	takes no parameter. An unknown query parameter is ignored, still 200

Sample requests

r = c.get("/license_info")

On the probed site, 104 bytes:

{
  "data": {"assigned": 4, "rule": "quantity", "free": 46, "total": 50, "type": "license-count"},
  "status": "success"
}

An unknown query parameter changes nothing:

r = c.get("/license_info", params={"prefs": "hours_per_day"})

{
  "data": {"assigned": 4, "rule": "quantity", "free": 46, "total": 50, "type": "license-count"},
  "status": "success"
}

key	type	means
`total`	integer	seats the site is licensed for
`assigned`	integer	seats spoken for
`free`	integer	`total - assigned` under `rule: quantity`; `-1` under `rule: unlimited`
`rule`	string	`quantity` or `unlimited`. Read it before reading `free`
`type`	string	`license-count` on the probed site

Response codes

status	when
200	always, including with an unrecognised query parameter
401	`Request rejected due to invalid credentials.`

Edge cases

The envelope is {"data": ..., "status": "success"}. There is no links and no links.self, so a client that reads every response through a JSON:API decoder fails on this one.
The site's own /spec.json example gives the five values as strings ("assigned": "56"). The site returns integers. Type-check rather than trusting the example.
free is -1, not 0 or null, when rule is unlimited. Subtracting it from total gives a number larger than the licence.
assigned is not the HumanUser row count and not the size of the GET /subscription_seat/user_subscriptions hash. On the probed site the three were 4, 24 and 14. Do not derive one from another.
/spec.json marks this call with the sudo_as_login security scope. A script token reads it without one, and so does a token acting as an Admin. Acting as an Artist it is 401 code 110 Must sudo as Administrator to query license information, the API naming the scope in its own refusal (probe 027).

GET /license_info