Tighten bypass target read contract

[ronaldvdmeer]

Summary

This PR tightens the contract of async_get_bypass_supply_temperature_target().

A parameter-specific GET /config?...&parameter=TempSupTgtZoneX read now either:

• returns a typed BypassSupplyTemperatureTarget
• raises DucoUnsupportedCapabilityError for unsupported zones
• raises DucoError if the requested field is missing from an otherwise successful response

Why

Live validation against 192.168.3.179 showed a clear distinction in API behavior:

• supported zones return the requested target
• unsupported zones return 400 {"Code":3,"Result":"FAILED"}

Because this helper already wraps the parameter-specific endpoint, silently returning None for a missing requested field is less precise than surfacing that as an error. The broader config surface can still model omission separately.

Included

• Client contract update
• Unit tests updated
• Generated API reference updated
• README and config docs updated

Validation

• PYTHONPATH=$PWD/src:$PWD .venv/bin/pytest
• .venv/bin/ruff check src tests
• .venv/bin/ruff format --check src tests
• PYTHONPATH=$PWD/src .venv/bin/mypy src
• .venv/bin/bandit -r src -ll

pip-audit only flagged the local .venv tool package pip 26.1.1 with an available fix in 26.1.2; no project dependency issue.

[Copilot]

Pull request overview

This pull request tightens the contract of the bypass supply temperature target convenience reader so that successful parameter-specific /config reads always produce a typed BypassSupplyTemperatureTarget, and missing target fields now raise an explicit DucoError instead of returning None. This aligns the helper’s behavior with observed device responses (supported zones return the field; unsupported zones return a typed “unsupported capability” error).

Changes:

• Updated DucoClient.async_get_bypass_supply_temperature_target() to raise DucoError when the requested target field is absent from an otherwise valid /config response, and to return a non-optional typed model.
• Updated unit tests and API-reference generation tests to reflect the new error/return contract.
• Updated generated docs and user-facing documentation (README + config docs + API reference + changelog) to match the tightened behavior.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tools/api_reference.py	Updates generated API reference metadata notes to document the new “raise on missing field” contract.
tests/test_client.py	Adjusts unit test expectations from None to DucoError for missing bypass target fields.
tests/test_api_reference.py	Updates API reference content assertion to match new documentation text.
src/duco_connectivity/client.py	Changes helper return type to non-optional and raises DucoError if the target field is missing.
README.md	Updates user-facing documentation to describe the new behavior (typed result or explicit error).
docs/config.md	Updates behavior bullets and example code to reflect non-optional return and error on missing field.
docs/api-reference.md	Updates generated API reference signature and notes for the tightened contract.
CHANGELOG.md	Records the breaking/behavioral change under Unreleased “Changed”.

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