[1/6] Name every mounted route in requestEcosystem

[wickedOne]

Name every mounted route in requestEcosystem

Part 1 of six splitting #381 ("analytics dashboard") into reviewable pieces, as the review there asked for. #381 stays open as the umbrella and reference thread until the last of these lands; it is not meant to be merged.

Series: #388 route coverage · #389 ecosystem stats · #390 analytics page · #391 /stats breakdown · #392 Grafana dashboard · #393 source attribution

Independent of the other five and of #389; it can land on its own.

Five mounted routes were missing from requestEcosystem, so /apk, /helm, /homebrew, /generic and /swift reported their ecosystem label as other on proxy_requests_total and proxy_request_duration_seconds -- pooled with the UI, /health and /metrics, which belong to no ecosystem at all.

/apk reports as alpine, matching what the apk handler writes to the database. The other four report under their own name. other now means what it says.

The new test enumerates all 23 mounts, so the next route that is added and not named here fails rather than quietly joining other.

Label change

Traffic on those five routes moves out of other. A query or alert reading other as "everything unroutable" will see it shrink.