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

PrivaPub/Infrastructure/Geo/GeoUpdater.cs

@@ -1,4 +1,4 @@
-using MaxMind.Db;
+using MaxMind.Db;
 
 using Microsoft.Extensions.Options;
 
@@ -11,8 +11,8 @@ namespace PrivaPub.Infrastructure.Geo
 {
 	// Keeps the DB-IP Lite databases current by itself, so a deploy needs no timer and no root: once a day it checks
 	// whether each database was built this month and, if not, fetches this month's (or, early in the month, last month's),
-	// checks it opens as the right kind of database and swaps it in. This and SMTP are the server's only traffic that is not
-	// federation, which is why it has its own client instead of IFederationHttp.
+	// checks it opens as the right kind of database and swaps it in. This, CdnUpdater and SMTP are the server's only traffic
+	// that is not federation, which is why each has its own client instead of IFederationHttp.
 	public sealed class GeoUpdater : BackgroundService
 	{
 		public const string ClientName = "geo";