refactor(config): rewrite config parser

This PR refactors the configuration parser, replacing the old parser implementation with a new, more structured approach that includes validation and improved organization.

Key changes:
- Complete rewrite of the configuration parser using a map-based structure with built-in validation
- Addition of comprehensive validator functions for configuration values
- Renamed numerous configuration getter methods for better consistency

internal/http/server/httpd.go

@@ -60,7 +60,7 @@ func StartWebServer(store *storage.Storage, pool *worker.Pool) []*http.Server {
 				slog.Error("ACME HTTP challenge server failed", slog.Any("error", err))
 			}
 		}()
-		config.Opts.HTTPS = true
+		config.Opts.SetHTTPSValue(true)
 		httpServers = append(httpServers, challengeServer)
 	}
 
@@ -95,7 +95,7 @@ func StartWebServer(store *storage.Storage, pool *worker.Pool) []*http.Server {
 		case certFile != "" && keyFile != "":
 			server.Addr = listenAddr
 			startTLSServer(server, certFile, keyFile)
-			config.Opts.HTTPS = true
+			config.Opts.SetHTTPSValue(true)
 		default:
 			server.Addr = listenAddr
 			startHTTPServer(server)
@@ -148,7 +148,7 @@ func startUnixSocketServer(server *http.Server, socketFile string) {
 				slog.String("key_file", keyFile),
 			)
 			// Ensure HTTPS is marked as true if any listener uses TLS
-			config.Opts.HTTPS = true
+			config.Opts.SetHTTPSValue(true)
 			if err := server.ServeTLS(listener, certFile, keyFile); err != http.ErrServerClosed {
 				printErrorAndExit("TLS Unix socket server failed to start on %s: %v", socketFile, err)
 			}