Expand Windows deny-read globs without invoking ripgrep (#59250)

## What changed

Use the `ignore` crate to snapshot matching files and directories in-process, replacing the external `rg` scan and fallback walker. Remove scanner discovery from MXC sandbox dependency checks.

Keep case-insensitive matching and configured scan depth limits. Skip directory links below the scan root while following explicitly linked roots, and continue past missing or inaccessible entries.

## Testing

Update resolver tests to cover child directory links, linked scan roots, dangling links, and literal brackets in glob patterns.

GitOrigin-RevId: e7f02d4db1fd42958adc212bb54055710fa2e536

codex-rs/exec-server/Cargo.toml

@@ -85,7 +85,6 @@ tempfile = { workspace = true }
 
 [target.'cfg(windows)'.dependencies]
 codex-mxc-sandbox = { workspace = true }
-which = { workspace = true }
 windows-sys = { workspace = true, features = [
     "Win32_Foundation",
     "Win32_Security",

codex-rs/exec-server/src/sandbox_integrity/AGENTS.md

@@ -30,11 +30,6 @@ negatives. Backend glob/symlink nuances and writable hard-link aliases are not
 fully modeled. The separate glob scan can differ from enforcement's snapshot.
 Metrics describe observed checker outcomes, not accuracy or missed violations.
 
-MXC scanner discovery currently uses `which`, while enforcement uses
-`Command`. Their search-order and environment differences can select different
-executables or cause only one scan to use the internal walker. This is an accepted
-telemetry limitation for this phase; changing production scanner selection is deferred.
-
 These are accepted limitations of this phase, not requests to duplicate backend
 implementations. Review against this scope. Regressions in explicit policy
 handling, executor context, or reporting remain actionable; this is not a blanket

codex-rs/exec-server/src/sandbox_integrity/mxc.rs

@@ -13,29 +13,10 @@ pub(super) const NAME: &str = "windows_mxc";
 
 pub(super) fn critical_dependencies(
     request: &SandboxExecRequest,
-    policy: &FileSystemSandboxPolicy,
-    cwd: &AbsolutePathBuf,
+    _policy: &FileSystemSandboxPolicy,
+    _cwd: &AbsolutePathBuf,
 ) -> io::Result<Vec<Dependency>> {
-    let command_cwd = request.cwd.to_abs_path()?;
-    let mut dependencies = codex_and_launcher_dependencies(request);
-    if !policy
-        .get_unreadable_globs_with_cwd(cwd.as_path())
-        .is_empty()
-    {
-        let path = request
-            .env
-            .iter()
-            .find(|(key, _)| key.eq_ignore_ascii_case("PATH"))
-            .map(|(_, value)| value);
-        if let Ok(scanner) = which::which_in(
-            codex_mxc_sandbox::GLOB_SCAN_PROGRAM,
-            path,
-            command_cwd.as_path(),
-        ) {
-            dependencies.push(("glob_scanner", Ok(scanner)));
-        }
-    }
-    Ok(dependencies)
+    Ok(codex_and_launcher_dependencies(request))
 }
 
 pub(super) fn prepare_policy(