CDNs found by themselves, and servers followed through time

PrivaPub now finds CDNs three ways, best first: the address ranges the
CDNs publish (Cloudflare, Fastly, Amazon CloudFront, Bunny, Gcore,
Imperva), downloaded daily by CdnUpdater and kept in CdnRangeSet; the
CDN's fingerprint in the responses it already gets from a server
(EdgeHintsHandler on the federation client); and the networks that carry
only a CDN. The fixed ASN list is gone; ASNs shared with plain hosting
(AWS, DataPacket) no longer hide a server. A server's Geo records the
CDN, its domain and how it was found, and weekly snapshots now keep the
city and coordinates too.

Servers through time (ServerPlaces): /instances/:host/history lists a
server's weekly snapshots, a CDN-fronted server's geo names the CDN's
domain and where the server was before it (before_cdn), and
/api/privapub/v1/cdns and /cdns/:domain group servers by CDN with week
by week who joined and who left. Owner decisions recorded in ROADMAP.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

docs/INTEROP.md

@@ -810,8 +810,10 @@ a remote host.
 `GET /api/privapub/v1/instances/:host` returns cached NodeInfo (`metadata` extras: Misskey `themeColor`/`maxNoteTextLength`,
 Pleroma `features[]`/`federation.mrf_policies`), the instance API's icon and description, the delivery health our
 circuit breaker sees, and which signature scheme worked. Its `geo` is the public projection of where the server is
-(`precision` `city`, `country` or `cdn`, ROADMAP owner decision on server locations); `?host[]=` answers up to 40 at
-once, and this server describes itself the same way.
+(`precision` `city`, `country` or `cdn`, ROADMAP owner decision on server locations); a CDN-fronted server's names the
+CDN's domain, how it was found (`ranges`, `headers`, `asn`) and `before_cdn`, its last place before the CDN. `?host[]=`
+answers up to 40 at once, and this server describes itself the same way. `/instances/:host/history` lists its weekly
+snapshots; `/api/privapub/v1/cdns` and `/cdns/:domain` group servers by CDN, week by week.
 
 `software.name` → family, for display: