fix(test): set command CWD in empty_input CLI tests

The `test_cli_markdown_file_no_actions` and `test_cli_empty_markdown_file`
integration tests were failing on the Ubuntu CI runner. The error indicated
that the default output directory (`./project-generated`) could not be
created due to "No such file or directory".

This occurred because the tests did not explicitly set the Current Working
Directory (CWD) for the spawned `strux` command. The command inherited the
CWD from the test runner environment, which was problematic on the Ubuntu
runner, preventing relative directory creation.

This commit fixes the issue by adding `cmd.current_dir(temp_dir.path())`
to both tests in `tests/cli/empty_input.rs`. This ensures the `strux`
command executes with its CWD set to the temporary directory created by
`assert_fs`, providing a reliable and writable location for filesystem
operations and resolving the CI failures.

Author: Romelium

tests/cli/empty_input.rs

@@ -15,6 +15,7 @@ fn test_cli_empty_markdown_file() {
 
     let mut cmd = get_cmd();
     cmd.arg(md_path.path());
+    cmd.current_dir(temp_dir.path()); // <-- ADDED: Set CWD for the command
 
     cmd.assert()
         .success()
@@ -46,6 +47,7 @@ fn test_cli_markdown_file_no_actions() {
 
     let mut cmd = get_cmd();
     cmd.arg(md_path.path());
+    cmd.current_dir(temp_dir.path()); // <-- ADDED: Set CWD for the command
 
     cmd.assert()
         .success()