fix(cli): migrate setup model/provider pickers off simple_term_menu to curses

The setup provider->model sub-menu (and three sibling pickers) used
simple_term_menu.TerminalMenu, whose ESC and arrow-key handling was
unreliable across terminals — notably ESC failed to back out of the
model selection list on terminals that emit raw escape sequences (e.g.
Ghostty). The codebase already notes simple_term_menu 'conflicts with
/dev/tty' and causes 'ghost-duplication rendering', and a prior attempt
to migrate these (closed PR) confirmed the same root cause.

Route all four single-select pickers through the shared, already-hardened
curses_radiolist (which decodes raw CSI/SS3 escape sequences and handles
ESC consistently, fixed in #35776):

- auth.py _prompt_model_selection — model picker; the pricing column
  header and the unavailable-models block are passed as the radiolist
  description so they survive the curses screen clear. ESC now cancels.
- main.py _prompt_reasoning_effort_selection — reasoning-effort picker.
- main.py _model_flow_named_custom — named custom-provider model picker.
- main.py _remove_custom_provider — provider-removal picker.

simple_term_menu is no longer imported anywhere (only stale comments
referenced it; one in setup.py is corrected). The numbered-input
fallbacks are unchanged and still trigger on curses errors / non-TTY.

Tests: updated test_terminal_menu_fallbacks / test_reasoning_effort_menu
/ test_custom_provider_model_switch / test_model_provider_persistence to
drive the fallback via curses_radiolist errors instead of breaking
simple_term_menu. New test_setup_menu_curses_migration.py asserts each
picker routes through curses_radiolist, ESC cancels, and the pricing
header is preserved. Net -147/+183 (mostly the new test file; production
code shrinks by removing TerminalMenu boilerplate).

hermes_cli/setup.py

@@ -305,7 +305,7 @@ def prompt_checklist(title: str, items: list, pre_selected: list = None) -> list
     appended at the end — the user toggles items with Space and confirms
     with Enter on "Continue →".
 
-    Falls back to a numbered toggle interface when simple_term_menu is
+    Falls back to a numbered toggle interface when curses is
     unavailable.
 
     Returns: