docs: create 'Adding a Robot' embodiment cookbook (closes #64)

[DsThakurRawat]

Description

Adds docs/adding_a_robot.md, an 'Embodiment Cookbook' that provides a step-by-step tutorial for adding new robots (arms, drones, AGVs, etc.) to Reflex.

Key Additions:

• 4-Step Process: Clear instructions on creating JSON configs, placing presets, updating schema enums, and testing.
• Worked Examples:
  • MyArm-6: A 6-DOF robotic arm for warehouse/farm use.
  • SkyScout: A 5-DOF surveillance drone for retail/traffic monitoring.
• Vertical-Specific Guidance: Tailored recommendations on action spaces, control rates, camera setups, and safety constraints for:
  • Warehouse Robots
  • Farm Robotics
  • Aerial Drones
  • Retail Loss Prevention
  • Traffic Management AI

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Infrastructure / CI update

How Has This Been Tested?

• pytest tests/ passes locally
• reflex doctor sanity check
• Other (please specify): Verified formatting and cross-referenced with codebase/schema.

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have kept the PR scoped to a single concern (one concern per PR)

[rylinjames]

Thanks @DsThakurRawat — the 4-step structure of this cookbook is exactly the right teaching shape. Credit preserved via Co-Authored-By on the commit in the replacement PR.

The reason this didn't merge as-is: the example JSONs used field names that aren't in src/reflex/embodiments/schema.json — "labels", "mean"/"std" (instead of the schema's mean_action/std_action/mean_state/std_state), camera "width"/"height"/"encoding" (instead of resolution + color_space), and "workspace_bbox" (no such field). Anyone copy-pasting the examples would hit schema-violation errors at validation time.

The replacement PR rewrites both worked examples using only real schema fields, validates them against the live validate_embodiment_config() at PR time, and adds a "Validate before opening a PR" snippet so future contributors don't hit this same trap. It also reflects #132's optional gripper / new payload_release block and #133's --state-msg-type flag.

Closing in favor of the replacement PR. Please keep contributing!