Write motor configuration to servo hardware (LeRobot-style: PID, acceleration, gripper overload protection)

[HipsterBrown]

Consolidates salvageable ideas from #7 and #8 (both closed as stale), plus the already-documented acceleration_degs_per_sec_per_sec follow-up in CLAUDE.md.

Currently acceleration_degs_per_sec_per_sec is validated and stored on the hardware arm but never written to the servos (see CLAUDE.md "Gotchas"). More broadly, we don't push LeRobot-style motor tuning to the STS3215 registers.

Ideas to pull from the closed PRs

• feat: enhance servo movement detection and motor configuration #8 ConfigureMotors: disable torque → write PID gains + operating mode + gripper overload/load protection → re-enable torque, run during servo init.
• Make grab() intelligent and add speed to arm + gripper #7 servo_config.go (configureServosOptimal): LeRobot-style register writes — reduce response_delay (500µs→~2µs for faster bus comms), set maximum_acceleration (protocol v0 / STS only), PID gains. Gated on protocol version.

Scope

• Write acceleration_degs_per_sec_per_sec through to the servo maximum_acceleration register (closes the existing CLAUDE.md TODO).
• Extra gripper load/overload protection registers.
• EEPROM writes require torque disabled first — do this in the init path before enabling torque.
• Re-target against feetech-servo v0.6.0 (both source PRs predate it); confirm register-name/helper APIs.

Neither source branch is worth reviving directly (heavy conflicts, stale feetech), but the register maps and sequencing are a useful reference.