Calibration workflow improvement

[kaklik]

This PR improves calibration project metadata completeness.

Changes:

• Spectrum CSV export now writes calibration metadata into a CSV header, including averaged ENV values, device metadata, analog/digital module identification, and original source metadata.
• Calibration project files now store ENV values, device/module identification, and source metadata needed for later calibration document generation.
• Analog module serial number is preserved from $ADC, with fallback to $DOS hardware serial when needed.
• Instrument type metadata is resolved through existing xDOS-versions data via DeviceType / KNOWN_DEVICES_BY_NAME.
• .dosview_calib now stores spectrum CSV paths relative to the project file location, so moving a folder with the calib file and CSVs keeps links valid.
• Calibration projects now save and restore the current spectrum plot range.
• Added tests for parser module metadata, spectrum CSV metadata loading, relative project paths, and plot range validation.