feat(events): instrument plate readers, imagers, and thermocyclers

[VivienP]

Summary

Extends PyLabRobot's structured EventBus coverage to measurement and thermal frontends.

• adds semantic lifecycle events for PlateReader open/close and luminescence, absorbance, and fluorescence reads
• adds one imager.capture lifecycle per public capture request, including autofocus and auto-exposure workflows without exposing their internal attempts as event storms
• adds lifecycle events for stable Thermocycler lid, temperature, deactivation, and protocol operations
• preserves ImageReader composition without duplicate instrumentation
• adds canonical schemas, user references, and focused regression coverage

Event semantics

The new events follow the existing EventBus contract:

• started / completed / failed lifecycle records share one operation_id
• normal return values and original exceptions are preserved
• events identify direct PLR resources
• event construction remains lazy when no interested subscriber exists
• measurement matrices, image data, callback objects, backend kwargs, and full protocol objects are deliberately excluded from payloads

For imaging, autofocus and auto-exposure may perform multiple internal hardware captures, but one public capture() request produces one semantic imager.capture lifecycle.

For thermocycling, thermocycler.run_protocol.completed means that the backend coroutine returned successfully. It does not claim independent physical verification that the protocol finished on the instrument.

Intentionally out of scope

• run_pcr_profile as a separate lifecycle: it remains a composite of existing instrumented operations
• thermocycler wait/status polling
• parent/child or causal operation correlation
• persistence or transport of EventBus records
• hardware-state normalization
• raw measurement or image artifact capture

These can be addressed separately without expanding the EventBus contract in this PR.

Validation

• 226 passed, plus 29 subtests passed, across EventBus, plate-reading/imaging, and thermocycling suites
• python -m mypy pylabrobot — success across 729 source files
• python -m ruff check pylabrobot — passed
• python -m ruff format --check pylabrobot — passed
• git diff --check — passed
• documentation Sphinx build with warnings treated as errors — passed
• pip check — passed

No physical hardware was driven during validation.

[rickwierenga]

this file duplicates what's already documented in the event schemas file.

[rickwierenga]

i.d.

[rickwierenga]

thanks for the PR! tiny comment above

[VivienP]

Good catch, I fixed that. No code changes.