unified-exec: retain PathUri in command events (#28780)

## Why

App-server must report command events containing foreign-platform paths
without changing existing client or rollout path-string formats.

## What changed

- retain `PathUri` through exec command begin/end events
- convert cwd values to `LegacyAppPathString` at the app-server
compatibility boundary
- drop command actions with foreign paths and log them
- serialize rollout-trace cwd values using their inferred native path
representation
- restore Wine coverage for retained Windows cwd values and successful
completion

codex-rs/tui/src/chatwidget/tests/app_server.rs

@@ -521,7 +521,7 @@ async fn live_app_server_command_execution_strips_shell_wrapper() {
             item: AppServerThreadItem::CommandExecution {
                 id: "cmd-1".to_string(),
                 command: command.clone(),
-                cwd: test_path_buf("/tmp").abs(),
+                cwd: test_path_buf("/tmp").abs().into(),
                 process_id: None,
                 source: AppServerCommandExecutionSource::UserShell,
                 status: AppServerCommandExecutionStatus::InProgress,
@@ -543,7 +543,7 @@ async fn live_app_server_command_execution_strips_shell_wrapper() {
             item: AppServerThreadItem::CommandExecution {
                 id: "cmd-1".to_string(),
                 command,
-                cwd: test_path_buf("/tmp").abs(),
+                cwd: test_path_buf("/tmp").abs().into(),
                 process_id: None,
                 source: AppServerCommandExecutionSource::UserShell,
                 status: AppServerCommandExecutionStatus::Completed,