v.pref: fix regression of command flags not working, when there is a subfolder, named after the command, in the current working folder (#21647)

Author: ttytm

vlib/v/pref/pref.v

@@ -962,12 +962,11 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 					// arguments for e.g. fmt should be checked elsewhere
 					continue
 				}
-				if res.is_vsh && command_idx < i {
-					// Allow for `script.vsh abc 123 -option`, because -option is for the .vsh program, not for v
-					continue
-				}
-				if command == 'doc' {
-					// Allow for `v doc -comments file.v`
+				if command_idx < i && (res.is_vsh || (is_source_file(command)
+					&& command in known_external_commands)) {
+					// When running programs, let them be responsible for the arguments passed to them.
+					// E.g.: `script.vsh cmd -opt` or `v run hello_world.v -opt`.
+					// But detect unknown arguments when building them. E.g.: `v hello_world.v -opt`.
 					continue
 				}
 				err_detail := if command == '' { '' } else { ' for command `${command}`' }