fix: prevent masking gaps in workflow command logs (#1384)

Mask partially escaped workflow command output and complete one-character values while preserving literal output and stream line endings.

Fixes: https://gitea.com/gitea/runner/issues/300
Reviewed-on: https://gitea.com/gitea/runner/pulls/1384
Reviewed-by: bircni <[email protected]>

act/runner/command_test.go

@@ -193,6 +193,11 @@ func TestCommandLogWriter(t *testing.T) {
 		log   []string
 		masks []string
 	}{
+		{
+			name:  "mask commands decode modern and legacy escapes once",
+			steps: [][]string{{"::add-mask::%25", "##[add-mask]alpha beta%3Bgamma%5Ddelta%250A"}},
+			masks: []string{"%", "alpha beta;gamma]delta%0A"},
+		},
 		{
 			name: "applied commands are hidden unless echoed",
 			steps: [][]string{{