[Regression] Lots of "context canceled" messages in logs

[CryptoCopter]

Describe the bug

The issue described in #446 (which should have been fixed by #470) seems to be back.
At least, this is what my logs look like running v1.23.0:

Nov 08 15:59:02 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:02.266719139+01:00","level":"INFO","source":{"function":"main.main","file":"github.com/TecharoHQ/anubis/cmd/anubis/main.go","line":477},"msg":"listening","url":"http://localhost:8097","difficulty":6,"serveRobotsTXT":true,"target":"http://localhost:8096","version":"1.23.0","use-remote-address":false,"debug-benchmark-js":false,"og-passthrough":false,"og-expiry-time":86400000000000,"base-prefix":"","cookie-expiration-time":604800000000000,"rule-error-ids":{"ai-catchall":"8d404b6f750adefd","ai-clients":"b3728715388cb593","ai-crawlers-search":"b0faade6eb1303e1","ai-crawlers-training":"26301432c34cf028","alibaba-cloud":"bf584155dcd667f7","headless-chrome":"4d1dbaddfcc0f385","headless-chromium":"290aba64f1527af9","huawei-cloud":"226fab975ba79f2a","lightpanda":"44d2de56a972dc6d","tencent-cloud":"83c9434310aa9ae9","us-artificial-intelligence-scraper":"f9d6578d179b858b"},"public-url":""}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.28881919+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.294904235+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.295066672+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.295856171+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.296126921+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.297318869+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.303833454+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.501384425+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.501493971+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.501704969+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.502313987+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.502411241+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.502591891+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.5027234+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.503855785+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.520612224+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.521348263+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.534903004+01:00","level":"INFO","source":{"function":"github.com/TecharoHQ/anubis/lib.(*Server).issueChallenge","file":"github.com/TecharoHQ/anubis/lib/anubis.go","line":135},"msg":"new challenge issued","subsystem":"anubis","host":"media.splork.de","method":"GET","path":"/web/noto-sans-latin-400-normal.f5cd7b617bcb047bfaa4.woff2","user_agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:144.0) Gecko/20100101 Firefox/144.0","accept_language":"en-GB,en;q=0.5","priority":"","x-forwarded-for":"91.59.144.3","x-real-ip":"91.59.144.3","challenge":"019a63fb-203e-7cb9-b431-4044806fc9e6"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.552741785+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.552840781+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.565920327+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.566266499+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.736713216+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 15:59:53 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T15:59:53.737310063+01:00","level":"INFO","msg":"http: proxy error: context canceled"}
Nov 08 16:00:48 notinventedhere.splork.de anubis[29758]: {"time":"2025-11-08T16:00:48.0745204+01:00","level":"INFO","source":{"function":"github.com/TecharoHQ/anubis/lib.(*Server).issueChallenge","file":"github.com/TecharoHQ/anubis/lib/anubis.go","line":135},"msg":"new challenge issued","subsystem":"anubis","host":"media.splork.de","method":"GET","path":"/","user_agent":"Mozilla/5.0 (iPhone; CPU iPhone OS 14_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.4 Mobile/15E148 Safari/604.1","accept_language":"","priority":"","x-forwarded-for":"34.220.239.94","x-real-ip":"34.220.239.94","challenge":"019a63fb-f54a-7720-b3c9-b7be3f8c39a5"}

### Steps to reproduce

1. Check logs
2. See lots of errors

### Expected behavior

1. Check logs
2. Don't see errors

### Your operating system and its version.

Arch Linux

### Your browser and its version.

144.0.2 (aarch64) (macos)

### Additional context

_No response_

[Xe]

I'll work on fixing this. For now know that these logs are ineffectual and no action is required.