Use ApiPathString in app-server filesystem permission paths (#28367)

## Why

Clients running an app-server on one OS and an exec-server on another OS
need to be able to pass sandbox config to app-server that refers to
resources on the executor's foreign OS.

## What

`AbsolutePathBuf` can't represent these paths and we don't want users to
be exposed to `PathUri` yet, so this moves the public app-server API to
be expressed in terms of `ApiPathString`.

Stacked on #28165.

- change app-server v2 filesystem permission paths, including legacy
read/write roots, to `ApiPathString`
- localize API paths through `PathUri` when converting into the current
native core permission types
- make path-bearing permission conversions fallible and surface
localization failures instead of silently treating malformed grants as
ordinary denials
- propagate conversion failures through app-server and TUI approval
handling
- regenerate the app-server JSON and TypeScript schemas
- leave migration TODOs on native-path conversions so they can be
removed once core permission paths use `PathUri`

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

@@ -89,6 +89,8 @@ fn app_server_exec_approval_request_preserves_permissions_context() {
         .expect("absolute read path");
     let write_path = AbsolutePathBuf::try_from(PathBuf::from(test_path_display("/tmp/write")))
         .expect("absolute write path");
+    let read_api_path = ApiPathString::from_abs_path(&read_path);
+    let write_api_path = ApiPathString::from_abs_path(&write_path);
     let request = exec_approval_request_from_params(
         AppServerCommandExecutionRequestApprovalParams {
             thread_id: "thread-1".to_string(),
@@ -109,8 +111,8 @@ fn app_server_exec_approval_request_preserves_permissions_context() {
                     enabled: Some(true),
                 }),
                 file_system: Some(AppServerAdditionalFileSystemPermissions {
-                    read: Some(vec![read_path.clone()]),
-                    write: Some(vec![write_path.clone()]),
+                    read: Some(vec![read_api_path.clone()]),
+                    write: Some(vec![write_api_path.clone()]),
                     glob_scan_max_depth: None,
                     entries: None,
                 }),
@@ -136,8 +138,8 @@ fn app_server_exec_approval_request_preserves_permissions_context() {
                 enabled: Some(true),
             }),
             file_system: Some(AppServerAdditionalFileSystemPermissions {
-                read: Some(vec![read_path]),
-                write: Some(vec![write_path]),
+                read: Some(vec![read_api_path]),
+                write: Some(vec![write_api_path]),
                 glob_scan_max_depth: None,
                 entries: None,
             }),
@@ -274,6 +276,8 @@ fn app_server_request_permissions_preserves_file_system_permissions() {
         .expect("absolute read path");
     let write_path = AbsolutePathBuf::try_from(PathBuf::from(test_path_display("/tmp/write")))
         .expect("absolute write path");
+    let read_api_path = ApiPathString::from_abs_path(&read_path);
+    let write_api_path = ApiPathString::from_abs_path(&write_path);
     let cwd =
         AbsolutePathBuf::try_from(PathBuf::from(test_path_display("/tmp"))).expect("absolute cwd");
 
@@ -290,13 +294,14 @@ fn app_server_request_permissions_preserves_file_system_permissions() {
                 enabled: Some(true),
             }),
             file_system: Some(AppServerAdditionalFileSystemPermissions {
-                read: Some(vec![read_path.clone()]),
-                write: Some(vec![write_path.clone()]),
+                read: Some(vec![read_api_path]),
+                write: Some(vec![write_api_path]),
                 glob_scan_max_depth: None,
                 entries: None,
             }),
         },
-    });
+    })
+    .expect("API paths should convert to native paths");
 
     assert_eq!(
         request.permissions,