Generate automatic and manual conversation recaps (#40705)

## Why

Users returning to a conversation need a short summary of its recent progress and next steps.

## What changed

- Generate a recap for eligible idle, unfocused conversations and add it to the transcript.
- Add `/recap` to request the same summary on demand, with visible progress and actionable errors.
- Keep recap requests bounded and isolated, reject stale results, and retry only automatic failures.

## Testing

- Cover automatic and manual generation, request eligibility, failure handling, loading-state cleanup, and temporary-thread configuration.

GitOrigin-RevId: 926a88d6996d67a42809ce2c4091b13fca882b52

codex-rs/tui/src/slash_command.rs

@@ -38,6 +38,7 @@ pub enum SlashCommand {
     App,
     Init,
     Compact,
+    Recap,
     Plan,
     Goal,
     Agents,
@@ -90,6 +91,7 @@ impl SlashCommand {
             SlashCommand::New => "start a new chat during a conversation",
             SlashCommand::Init => "create an AGENTS.md file with instructions for Codex",
             SlashCommand::Compact => "summarize conversation to prevent hitting the context limit",
+            SlashCommand::Recap => "summarize the current conversation now",
             SlashCommand::Review => "review my current changes and find issues",
             SlashCommand::Rename => "rename the current thread",
             SlashCommand::Resume => "resume a saved chat",
@@ -210,6 +212,7 @@ impl SlashCommand {
             | SlashCommand::Fork
             | SlashCommand::Init
             | SlashCommand::Compact
+            | SlashCommand::Recap
             | SlashCommand::Export
             | SlashCommand::Keymap
             | SlashCommand::Vim