`hermes login` was removed in favor of `hermes auth` / `hermes model`, but
the subparser still validated `--provider` against a hardcoded choices list
(nous, openai-codex, xai-oauth). Running `hermes login --provider anthropic`
therefore crashed in argparse with `invalid choice: 'anthropic'` *before* the
deprecation handler could print the redirect to `hermes model` — so a user
trying to authenticate a perfectly valid provider just saw a hard error and
assumed the feature was broken rather than relocated.
- Drop the restrictive `choices=` so every `--provider` value reaches the
deprecation handler (which ignores the value and prints guidance).
- Omit the subparser `help=` kwarg so the dead command no longer advertises
itself in `hermes --help` (#24756). Avoids the `==SUPPRESS==` placeholder
leak that `help=argparse.SUPPRESS` emits for a top-level subparser on 3.12+.
- `hermes login [--flags]` still reaches the actionable deprecation message
for old scripts/aliases; `hermes login --help` shows the redirect.
Picks up the intent of the inactivity-closed #24902, rebased onto the
post-refactor parser location (hermes_cli/subcommands/login.py) and extended
to fix the whole bug class (any provider value), not just hiding from --help.
Tests: parametrized provider acceptance + help-suppression (no SUPPRESS leak).
