feat(opentrons): add new-architecture OT-2 driver

[rickwierenga]

Summary

Adds an Opentrons OT-2 driver following PyLabRobot's new device architecture.

The driver lives in pylabrobot/opentrons/ot2/ and models each mounted pipette as an OT2Pipette object. It communicates directly with the robot's HTTP API through a new asynchronous JSON-over-HTTP transport.

Features

• Discover left and right mounted pipettes during setup
• Support Gen1 and Gen2 single-channel OT-2 pipettes
• Home the robot and move pipettes in robot-frame coordinates
• Pick up, return, discard, aspirate, dispense, and mix
• Update and roll back PLR tip and volume trackers around commands
• Load standard Opentrons tip racks by their official definitions
• Generate schema-valid definitions for other PLR tip racks
• Stop the active run using the current run-action API, with legacy fallbacks
• List connected Opentrons modules
• Reject unreachable, non-finite, and negative-Z movements locally

Differences from the legacy backend

• Uses a plain device class instead of the legacy backend hierarchy
• Exposes real left/right pipette objects instead of mount dictionaries
• Owns its HTTP transport instead of using the global ot_api client
• Uses current fixed-trash and run-stop payloads
• Preserves official tip-rack identities for tip-length calibration
• Rolls back PLR tracker changes when commands fail
• Rejects multi-channel operations instead of tracking an eight-channel operation as one tip and one well

Documentation

Adds a runnable tutorial at:

docs/user_guide/opentrons/ot2/hello-world.ipynb

The notebook covers calibration, networking, deck setup, pipette discovery, tip handling, mixing, transfer, disposal, homing, and teardown.

Validation

• OT-2, HTTP, deck, and geometry tests: 24 passed
• Ruff
• Mypy
• Sphinx warning-as-error build
• Notebook validation and code-cell parsing
• Generated tip-rack definition validated against historical and current Opentrons labware schema v2
• Physical OT-2 hardware test

Current limitations

• Multi-channel liquid operations are not implemented
• Custom tip racks may require measured offsets and use nominal tip geometry
• Opentrons per-labware position-check offsets are not automatically applied to liquid labware addressed through PLR coordinates
• Opentrons resource definitions currently require internet access on first use

Hardware status

This driver has not yet been tested on physical hardware. setup() logs an explicit warning until a staged single-channel hardware test has passed.