Naming, layout and comments: descriptive full-word names, one item per line in wrapped calls and literals, and doc comments on exported names

Short and single-letter names in application code become full words (tests
keep theirs). Wrapped calls, signatures and composite literals put one item
per line, and one-line function bodies are expanded. Exported names and
groups of constants get doc comments, and comments refer to the renamed
identifiers.

internal/config/conf_logging.go

@@ -50,7 +50,8 @@ func (c *JSCLogging) validate(key string, value any) error {
 		case "debug", "info", "warn", "error":
 		default:
 			return errors.New(
-				"invalid log level. Must be one of: debug, info, warn, error")
+				"invalid log level. Must be one of: debug, info, warn, error",
+			)
 		}
 	}
 	return nil