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/protocol_requests.rs

@@ -30,7 +30,16 @@ impl ChatWidget {
                 self.on_elicitation_request(request_id, params);
             }
             ServerRequest::PermissionsRequestApproval { params, .. } => {
-                self.on_request_permissions(request_permissions_from_params(params));
+                // TODO(anp): Remove this native-path localization error path once core permission
+                // paths remain PathUri after crossing the app-server boundary.
+                match request_permissions_from_params(params) {
+                    Ok(event) => self.on_request_permissions(event),
+                    Err(err) => {
+                        self.add_error_message(format!(
+                            "failed to localize requested filesystem paths: {err}"
+                        ));
+                    }
+                }
             }
             ServerRequest::ToolRequestUserInput { params, .. } => {
                 self.on_request_user_input(params);
@@ -62,6 +71,17 @@ impl ChatWidget {
         completion: Option<(i64, codex_app_server_protocol::AutoReviewDecisionSource)>,
         action: GuardianApprovalReviewAction,
     ) {
+        // TODO(anp): Remove this native-path localization error path once core permission paths
+        // remain PathUri after crossing the app-server boundary.
+        let action = match action.try_into() {
+            Ok(action) => action,
+            Err(err) => {
+                self.add_error_message(format!(
+                    "failed to localize guardian filesystem paths: {err}"
+                ));
+                return;
+            }
+        };
         let (completed_at_ms, decision_source) = match completion {
             Some((completed_at_ms, decision_source)) => {
                 (Some(completed_at_ms), Some(decision_source))
@@ -128,7 +148,7 @@ impl ChatWidget {
                     GuardianAssessmentDecisionSource::Agent
                 }
             }),
-            action: action.into(),
+            action,
         });
     }