* fix(cli): send User-Agent on jobnet and jobdanmark API requests
apiFetch/apiPost hit the portals' APIs without a User-Agent header, while every other Danish-portal CLI sends one on purpose (jobbank exports USER_AGENT and its tests assert it; jobindex sets it on htmlFetch). Requests without one are rejected by the portals' bot filters.
* fix(cli): satisfy strict typecheck in user-agent regression test
* refactor(cli): reframe user-agent tests as honest self-identification
* docs(changelog): entry for #283 user-agent self-identification
