Fix roller shutter calibration with unknown position

[klew]

Motivation

• A refactor changed the default calibration state so a restored UNKNOWN_POSITION could be treated as calibrated when opening/closing times exist, causing absolute OPEN commands to compute movement against -1 and trigger the wrong motor direction.
• The intent is to ensure a roller shutter restored with unknown position is considered not calibrated so commands that rely on a known position behave safely.

Description

• Update RollerShutterInterface::isCalibrated() to return false when getCalibrate() is set or getCurrentPosition() == UNKNOWN_POSITION, and only consider time-based calibration when a known position exists; the change is in src/supla/control/roller_shutter_interface.cpp.
• Add a regression unit test loadedUnknownPositionIsNotCalibrated to extras/test/RollerShutterTests/roller_shutter_tests.cpp that restores a state with UNKNOWN_POSITION and asserts the device remains uncalibrated and an absolute open target starts opening (checks getCurrentDirection() is UP_DIR).
• Keep behavior for time-setting vs position-based channels consistent by guarding calibration checks with the unknown-position condition.

Testing

• Ran git diff --check which reported no issues.
• Attempted to run the test build via cmake -S extras/test -B /tmp/supla-device-test-build but it failed during FetchContent cloning of https://github.com/nlohmann/json.git (CONNECT tunnel HTTP 403), so the test binary could not be built in this environment.
• Added the unit test as coverage for the regression; it will run in CI or a developer environment where FetchContent dependencies can be retrieved.

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Handle partial targets safely when position is unknown

By forcing isCalibrated() to return false whenever getCurrentPosition()==UNKNOWN_POSITION, restored devices now enter the uncalibrated path in RollerShutter::onTimer; in that path, targets other than fully open/closed (0/100) leave newDirection as STOP but still fall through to startOpening() when currently stopped. This means a valid absolute command like 50% after reboot with unknown position will now always open, which contradicts the existing non-calibrated logic comment and can move in the wrong direction for close-oriented targets.

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