Add Franka NMG benchmarks and demo path

[skywhite1024]

Description

This PR adds and wires up Franka neural motion generation benchmark coverage, including planner-level trials and the Franka pick-place demo/benchmark path.

It includes:

• Franka planner benchmarks for demo-matched offsets and reachable-FK waypoint banks.
• Franka pick-place demo/benchmark support with selectable IK/NMG planners and automated demo execution.
• Neural planner asset resolution and documentation updates for local/HuggingFace checkpoints.
• Atomic-action trajectory integration updates and tests for planner, trajectory, solver, and benchmark behavior.

Motivation: make it easier to compare IK-style planning against the experimental NMG backend on Franka, while keeping downstream pick-place validation separate from planner-only metrics.

Dependencies: adds huggingface-hub for neural planner checkpoint download support.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which improves an existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (existing functionality will not work without user modification)
• Documentation update

Screenshots

N/A

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.