Add MAPPO Device Connect dashboard Learning Path

[armwaheed]

Summary

• add a focused Part 2 Learning Path that uses the Arm Device Connect dashboard as the GUI
• continue the MAPPO training and actor-export workflow from Add mappo navigation learning path #3680
• serve, download, inspect, arm, and smoke-test the exported actor through a simulated Device Connect device
• keep the dashboard on loopback, use SSH port forwarding, and leave physical motion disabled
• pin the demo commit and Python dependencies used for validation

Validation

• completed an end-to-end dashboard dry run with Device Connect 0.2.5: model discovery, download, compatibility inspection, selection, arming, and basic_test.py (PASS)
• hugo --minify
• hugo --buildDrafts --minify
• python3 tools/verify_index_fields.py ...
• repository Learning Path test runner (maintenance execution is off for this draft)
• ruff check dashboard
• all 283 dashboard tests on Python 3.11

Publication blocker

The required armwaheed/mappo-arm-cloud-physical-ai repository is currently private. This PR is intentionally a draft, and the Learning Path retains draft: true. The demo repository must be made publicly readable, or the dashboard code must move to another public source, before this Learning Path is published.