Remove the Plan mode composer nudge (#40200)

## What changed

- Keep the normal composer footer visible when a draft contains the word `plan`.
- Remove the contextual “Create a plan?” prompt, its Escape dismissal behavior, and its per-thread dismissal state.

## Testing

- Update wide and narrow composer snapshots to cover the standard footer for plan-related drafts.

GitOrigin-RevId: 1a3c8cfce9d4effa2149790975133f652aa7c914

codex-rs/tui/src/chatwidget.rs

@@ -667,11 +667,6 @@ pub(crate) struct ChatWidget {
     #[cfg(test)]
     pet_image_support_override: Option<crate::pets::PetImageSupport>,
     thread_id: Option<ThreadId>,
-    /// Nudge dismissals that should survive draft edits within the current thread scope.
-    ///
-    /// The nudge is only a discovery aid, so once a user dismisses it or enters Plan mode we keep it
-    /// hidden for that thread instead of resurfacing it on every matching draft.
-    dismissed_plan_mode_nudge_scopes: HashSet<PlanModeNudgeScope>,
     thread_name: Option<String>,
     thread_rename_block_message: Option<String>,
     active_side_conversation: bool,
@@ -835,31 +830,12 @@ enum SessionConfiguredDisplay {
     SideConversation,
 }
 
-/// Scope used to keep Plan-mode nudge dismissal local to one conversation context.
-#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
-enum PlanModeNudgeScope {
-    /// Drafts entered before the server has assigned a thread id.
-    NewThread,
-    /// Drafts associated with one configured thread.
-    Thread(ThreadId),
-}
-
 #[derive(Debug, Clone, Copy, Eq, PartialEq)]
 pub(crate) enum TurnAbortReason {
     Interrupted,
     BudgetLimited,
 }
 
-/// Returns whether `text` contains the standalone word `plan`.
-///
-/// This intentionally mirrors the App suggestion heuristic instead of trying to infer broader
-/// planning intent from substrings such as `planning`. Slash and shell drafts still match here so
-/// callers can keep lexical matching separate from presentation policy.
-fn contains_plan_keyword(text: &str) -> bool {
-    text.split(|ch: char| !ch.is_alphanumeric() && ch != '_')
-        .any(|word| word.eq_ignore_ascii_case("plan"))
-}
-
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 enum ThreadItemRenderSource {
     Live,
@@ -1224,7 +1200,6 @@ impl ChatWidget {
         if let Some(pet) = self.ambient_pet.as_ref() {
             pet.schedule_next_frame();
         }
-        self.refresh_plan_mode_nudge();
         self.refresh_goal_status_indicator_for_time_tick();
         if self.terminal_title_shows_action_required() != self.last_terminal_title_requires_action {
             self.refresh_terminal_title();