Improve logging

- Actually log useful information at their respective log level.
- Add logs in hot-paths to be able to deep-dive and debug specific
requests (see server/handler.go)
- Remove zerologger and instead use custom logger that doesn't log
JSON (directly inspired by https://codeberg.org/Codeberg/moderation/pulls/7).
- Add more information to existing fields(e.g. the host that the user is
visiting, this was noted by @fnetX).

server/try.go

@@ -41,6 +41,7 @@ func tryUpstream(ctx *fasthttp.RequestCtx, giteaClient *gitea.Client,
 	targetOptions.TargetRepo = targetRepo
 	targetOptions.TargetBranch = targetBranch
 	targetOptions.TargetPath = targetPath
+	targetOptions.Host = string(trimmedHost)
 
 	// Try to request the file from the Gitea API
 	if !targetOptions.Upstream(ctx, giteaClient, branchTimestampCache, fileResponseCache) {