feat: copy tweaks (#2502)

- For selectable options, use sentences starting in lowercase and not
ending with periods. To be honest I don't love this style, but better to
be consistent for now.
- Tweak some other strings.
- Put in more compelling suggestions on launch. Excited to put `/mcp` in
there next.

codex-rs/tui/src/chatwidget.rs

@@ -771,7 +771,7 @@ impl ChatWidget<'_> {
         }
 
         self.bottom_pane.show_selection_view(
-            "Select Approvals Mode".to_string(),
+            "Select Approval Mode".to_string(),
             None,
             Some("Press Enter to confirm or Esc to go back".to_string()),
             items,

codex-rs/tui/src/history_cell.rs

@@ -168,7 +168,8 @@ pub(crate) fn new_session_info(
             Line::from("".dim()),
             Line::from(format!(" /init - {}", SlashCommand::Init.description()).dim()),
             Line::from(format!(" /status - {}", SlashCommand::Status.description()).dim()),
-            Line::from(format!(" /diff - {}", SlashCommand::Diff.description()).dim()),
+            Line::from(format!(" /approvals - {}", SlashCommand::Approvals.description()).dim()),
+            Line::from(format!(" /model - {}", SlashCommand::Model.description()).dim()),
             Line::from("".dim()),
         ];
         PlainHistoryCell { lines }

codex-rs/tui/src/slash_command.rs

@@ -38,7 +38,7 @@ impl SlashCommand {
             SlashCommand::Diff => "show git diff (including untracked files)",
             SlashCommand::Mention => "mention a file",
             SlashCommand::Status => "show current session configuration and token usage",
-            SlashCommand::Model => "choose a model preset (model + reasoning effort)",
+            SlashCommand::Model => "choose what model and reasoning effort to use",
             SlashCommand::Approvals => "choose what Codex can do without approval",
             SlashCommand::Mcp => "list configured MCP tools",
             SlashCommand::Logout => "log out of Codex",