feat: support FORCE_COLOR environment variable (#671)

https://force-color.org, covers NO_COLOR too.

FORCE_COLOR takes precedence over NO_COLOR, as in the standard's example
implementation.

Author: scop

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Unconditionally enable colors if the [FORCE_COLOR](https://force-color.org) environment variable is set to a non-empty value.
+
 ## [3.28.0] - 2026-01-14
 
 ### Added

internal/core/core.go

@@ -36,11 +36,10 @@ func BuildRootCmd(conf *config.Config) cobra.Command {
 				return err
 			}
 
-			// detect desired colour output
+			// detect desired colour output, respect https://force-color.org (FORCE_COLOR, NO_COLOR)
 			switch {
-			case conf.GlobalFlags.ForceColours == config.True:
+			case conf.GlobalFlags.ForceColours == config.True || os.Getenv("FORCE_COLOR") != "":
 				text.EnableColors()
-			// Environment variable with US spelling to support https://no-color.org
 			case conf.GlobalFlags.NoColours == config.True || os.Getenv("NO_COLOR") != "":
 				text.DisableColors()
 			case conf.GlobalFlags.OutputFormat != config.ValueOutputHuman: