Sync collaboration mode naming across Default prompt, tools, and TUI (#10666)

## Summary
- add shared `ModeKind` helpers for display names, TUI visibility, and
`request_user_input` availability
- derive TUI mode filtering/labels from shared `ModeKind` metadata
instead of local hardcoded matches
- derive `request_user_input` availability text and unavailable error
mode names from shared mode metadata
- replace hardcoded known mode names in the Default collaboration-mode
template with `{{KNOWN_MODE_NAMES}}` and fill it from
`TUI_VISIBLE_COLLABORATION_MODES`
- add regression tests for mode metadata sync and placeholder
replacement

## Notes
- `cargo test -p codex-core` integration target (`tests/all`) still
shows pre-existing env-specific failures in this environment due missing
`test_stdio_server` binary resolution; core unit tests are green.

## Codex author
`codex resume 019c26ff-dfe7-7173-bc04-c9e1fff1e447`

codex-rs/tui/src/chatwidget.rs

@@ -5490,11 +5490,10 @@ impl ChatWidget {
         if !self.collaboration_modes_enabled() {
             return None;
         }
-        match self.active_mode_kind() {
-            ModeKind::Plan => Some("Plan"),
-            ModeKind::Default => Some("Default"),
-            ModeKind::PairProgramming | ModeKind::Execute => None,
-        }
+        let active_mode = self.active_mode_kind();
+        active_mode
+            .is_tui_visible()
+            .then_some(active_mode.display_name())
     }
 
     fn collaboration_mode_indicator(&self) -> Option<CollaborationModeIndicator> {

codex-rs/tui/src/collaboration_modes.rs

@@ -2,15 +2,11 @@ use codex_core::models_manager::manager::ModelsManager;
 use codex_protocol::config_types::CollaborationModeMask;
 use codex_protocol::config_types::ModeKind;
 
-fn is_tui_mode(kind: ModeKind) -> bool {
-    matches!(kind, ModeKind::Plan | ModeKind::Default)
-}
-
 fn filtered_presets(models_manager: &ModelsManager) -> Vec<CollaborationModeMask> {
     models_manager
         .list_collaboration_modes()
         .into_iter()
-        .filter(|mask| mask.mode.is_some_and(is_tui_mode))
+        .filter(|mask| mask.mode.is_some_and(ModeKind::is_tui_visible))
         .collect()
 }
 
@@ -31,7 +27,7 @@ pub(crate) fn mask_for_kind(
     models_manager: &ModelsManager,
     kind: ModeKind,
 ) -> Option<CollaborationModeMask> {
-    if !is_tui_mode(kind) {
+    if !kind.is_tui_visible() {
         return None;
     }
     filtered_presets(models_manager)