Support inline permission profile selection with /permissions (#54383)

## What changed

Allow `/permissions <profile-id>` to select a built-in or custom permission profile, for example `/permissions :read-only`. Support `:ask-for-approval` and `:approve-for-me` aliases while preserving feature gates, profile requirements, full-access confirmation, and Windows sandbox setup.

Hold queued input until the selection is confirmed, and retain it on cancellation or failure. Reload custom profile definitions on re-selection without leaving unchanged requests pending.

## Testing

Add coverage for unknown and disabled profiles, approval aliases, confirmation and cancellation, discovery retries, Windows sandbox setup, and queued prompts waiting for server confirmation.

GitOrigin-RevId: ada38d3cfc6d6ac4e84ce5645fe33432c55d63cc

codex-rs/tui/src/slash_command.rs

@@ -174,6 +174,7 @@ impl SlashCommand {
             self,
             SlashCommand::Review
                 | SlashCommand::Model
+                | SlashCommand::Permissions
                 | SlashCommand::Rename
                 | SlashCommand::New
                 | SlashCommand::Clear