feat(omx): add SMPS2DYNAMIXEL power connection guidance

[Woojin-Crive]

The interactive Follower guide currently ends after TTL cabling. This update adds the external-power connection sequence for both BIC30 and XL4015 builds: check the OpenRB-150 VIN(DXL) jumper, connect SMPS2DYNAMIXEL to the spare DYNAMIXEL socket, and insert the 12 V adapter plug with mains disconnected. The existing 72 steps and completion identifiers are preserved.

The Leader controller now includes a seated +5V jumper that follows the board during installation. Both models use a detailed closed-top shunt with a molded grip and recessed contacts.

• Add the SMPS2DYNAMIXEL board, conversion harness and DC plug visuals, with connector close-ups and the existing motor branches retained.
• Update completion guidance and add regression coverage for jumper motion, socket use and connection order.
• Document the model references and reconstructed details. Only web-ready model assets are included; original CAD, hardware photographs and render outputs are excluded.
• Remove the OMX development section from the root README; viewer build and asset documentation remain in docusaurus/omx-assembly/README.md.

Validation

• npm run test:omx — 37 tests passed.
• npm run typecheck and viewer formatting checks passed.
• GitHub docs_ci passed. The local English production build also passed. The viewer is 120.3 MiB, below its 125 MiB size budget.
• The English build reports HTML minifier warnings in the unchanged AI Worker cuMotion page.
• Browser review of the deployed power steps and jumper positions; model hashes and unchanged existing geometry verified. Physical electrical operation was not tested.

Preview the Follower power connection