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.Tests/Support/Host/PrivaPubHost.cs

@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
@@ -75,6 +75,7 @@ namespace PrivaPub.Tests.Support.Host
 			["Federation:FetchLinkPreviews"] = "false",
 			["Registrations:Mode"] = "Open",
 			["Statistics:Geo:AutoUpdate"] = "false",
+			["Statistics:Cdn:AutoUpdate"] = "false",
 			["Media:Root"] = _mediaRoot,
 			["Logging:LogLevel:Default"] = "Warning",
 			["Serilog:MinimumLevel:Default"] = Environment.GetEnvironmentVariable("PRIVAPUB_TEST_LOGS") == "1" ? "Information" : "Fatal"