Use in-process parsing for PowerShell command classification (#39602)

## What changed

- Route PowerShell wrapper extraction and Windows safe-command classification through the tree-sitter lowerer.
- Compile the PowerShell AST subprocess parser only in tests, where it remains available as an oracle.

GitOrigin-RevId: 3690bc32e8987ac9de820ef39ff7401d98ea8d83

codex-rs/shell-command/src/powershell.rs

@@ -2,7 +2,6 @@ use std::path::PathBuf;
 
 use codex_utils_absolute_path::AbsolutePathBuf;
 
-use crate::command_safety::try_parse_powershell_ast_commands;
 use crate::command_safety::try_parse_powershell_commands;
 use crate::shell_detect::ShellType;
 use crate::shell_detect::detect_shell_type;
@@ -74,13 +73,13 @@ pub fn extract_powershell_command(command: &[String]) -> Option<(&str, &str)> {
 /// Parse the script body from a top-level PowerShell wrapper into argv-like commands.
 ///
 /// This is intentionally narrower than the Windows safe-command parser: it only unwraps the
-/// `-Command`/`-c` body from a PowerShell invocation we already recognize, then delegates the
-/// script itself to the PowerShell AST parser.
+/// `-Command`/`-c` body from a PowerShell invocation we already recognize, then lowers the
+/// script in-process.
 pub fn parse_powershell_command_into_plain_commands(
     command: &[String],
 ) -> Option<Vec<Vec<String>>> {
-    let (executable, script) = extract_powershell_command(command)?;
-    try_parse_powershell_ast_commands(executable, script)
+    let (_, script) = extract_powershell_command(command)?;
+    try_parse_powershell_commands(script)
 }
 
 /// Parse literal PowerShell commands without starting a PowerShell executable.