CLI help advertises an unimplemented --cfg-options flag

Problem

The --options help text in all three SALMONN entry points says that the option is deprecated and users should switch to --cfg-options. However, none of the parsers registers a --cfg-options argument.

Affected source: salmonn branch at a58bba799a2eec05df09df102553f5c623808c12.

Affected entry points:

• train.py
• cli_inference.py
• web_demo.py

Reproduction

Search the parser definitions for --options and --cfg-options. Each entry point registers --options, while --cfg-options appears only inside the help string.

Passing the recommended flag therefore produces an unrecognized-argument error once the application's dependencies are installed.

Expected behavior

CLI help should describe the option that users can actually pass, or the recommended replacement should be implemented consistently.

Actual behavior

The help directs users away from the working flag to a flag that does not exist.

Suggested fix

Keep the existing --options interface and change its help text to describe the supported key=value overrides. This avoids an unnecessary CLI compatibility change.

Start in train.py, cli_inference.py, and web_demo.py by inspecting the parser definitions for --options and --cfg-options. Update the existing --options help text so it describes the supported key=value overrides without advertising an unavailable flag, then verify the help output and argument parsing for all three entry points.