[feat] add /status slash command (#1873)

- Added a `/status` command, which will be useful when we update the
home screen to print less status.
- Moved `create_config_summary_entries` to common since it's used in a
few places.
- Noticed we inconsistently had periods in slash command descriptions
and just removed them everywhere.
- Noticed the diff description was overflowing so made it shorter.

codex-rs/exec/src/event_processor.rs

@@ -1,7 +1,5 @@
 use std::path::Path;
 
-use codex_common::summarize_sandbox_policy;
-use codex_core::WireApi;
 use codex_core::config::Config;
 use codex_core::protocol::Event;
 
@@ -19,30 +17,6 @@ pub(crate) trait EventProcessor {
     fn process_event(&mut self, event: Event) -> CodexStatus;
 }
 
-pub(crate) fn create_config_summary_entries(config: &Config) -> Vec<(&'static str, String)> {
-    let mut entries = vec![
-        ("workdir", config.cwd.display().to_string()),
-        ("model", config.model.clone()),
-        ("provider", config.model_provider_id.clone()),
-        ("approval", config.approval_policy.to_string()),
-        ("sandbox", summarize_sandbox_policy(&config.sandbox_policy)),
-    ];
-    if config.model_provider.wire_api == WireApi::Responses
-        && config.model_family.supports_reasoning_summaries
-    {
-        entries.push((
-            "reasoning effort",
-            config.model_reasoning_effort.to_string(),
-        ));
-        entries.push((
-            "reasoning summaries",
-            config.model_reasoning_summary.to_string(),
-        ));
-    }
-
-    entries
-}
-
 pub(crate) fn handle_last_message(last_agent_message: Option<&str>, output_file: &Path) {
     let message = last_agent_message.unwrap_or_default();
     write_last_message_file(message, Some(output_file));