fix(cli): remove ogx stack rm command due to lack of CLI discovery (#5735)

## Summary
- Remove the `ogx stack rm` subcommand which was not discoverable
through the CLI
- Delete `src/ogx/cli/stack/remove.py` and its registration in
`stack.py`
- Reduces maintenance burden by removing dead code

## Test plan
- [ ] Verify `ogx stack --help` no longer shows `rm` subcommand
- [ ] Verify other stack subcommands (`run`, `list-apis`,
`list-providers`, etc.) still work
- [ ] Pre-commit checks pass

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Signed-off-by: Sébastien Han <seb@redhat.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: leseb

src/ogx/cli/stack/remove.py

@@ -15,7 +15,6 @@
 from .list_apis import StackListApis
 from .list_deps import StackListDeps
 from .list_providers import StackListProviders
-from .remove import StackRemove
 from .run import StackRun
 
 
@@ -47,6 +46,5 @@ def __init__(self, subparsers: argparse._SubParsersAction):
         StackListProviders.create(subparsers)
         StackRun.create(subparsers)
         StackLetsGo.create(subparsers)
-        StackRemove.create(subparsers)
         StackListBuilds.create(subparsers)
         print_subcommand_description(self.parser, subparsers)