docs: expand README with current workflows

[logohere]

Summary

• restore concrete current-feature documentation without bringing back the old internal/status-heavy prose
• add a compact feature table
• document agent sessions, headful console, scoped capability calls, and recurring tasks
• expand telemetry/replay, navigation, compute/CUDA, hardware, ROS 2, and safety sections
• expand crate and repository layout descriptions
• keep quick start and demo near the top

No runtime behavior changes.