Unify EmbodiChain CLI commands

[yuecideng]

Description

This PR unifies EmbodiChain's public command-line tools under the embodichain <command> [args] entry point.

It adds lazy command dispatch for data assets, SimReady processing, URDF decomposition, benchmarks, and workspace cache management; forwards each command to its complete parser so nested --help output is accurate; and preserves the existing module entry points for compatibility. It also aligns required/default arguments, updates command examples across the documentation, and adds CLI routing tests.

Motivation: several user-facing tools still required deep python -m ... paths, while existing unified subcommands exposed empty help parsers and eagerly loaded unrelated heavy modules.

Dependencies: none.

Issue: N/A (requested directly).

Type of change

• Enhancement (non-breaking change which improves an existing functionality)

Screenshots

Not applicable; this change affects command-line interfaces and documentation.

Validation

• black . --extend-exclude '(^|/)\\.worktrees/' — 470 files unchanged
• pytest -q tests — 711 passed, 99 skipped
• CLI and nested benchmark --help smoke checks
• Python compileall and wheel packaging checks

Checklist

• I have run the black . command to format the code base.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• Dependencies have been updated, if applicable (no new dependencies).

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.