feat: robin (#7882)

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Co-authored-by: Dylan Hurd <dylan.hurd@openai.com>

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__model_selection_popup.snap

@@ -10,7 +10,8 @@ expression: popup
   2. gpt-5.1-codex                Optimized for codex.
   3. gpt-5.1-codex-mini           Optimized for codex. Cheaper, faster, but
                                   less capable.
-  4. robin                        Robin
+  4. gpt-5.2                      Latest frontier model with improvements
+                                  across knowledge, reasoning and coding
   5. gpt-5.1                      Broad world knowledge with strong general
                                   reasoning.