Use altitude-based barometric pressure gauge ranges

[mot-yelraf]

Summary

Barometric gauges now derive raw/absolute pressure bounds from the altitude entered in General Settings, rounding outward to 10 hPa or 0.1 inHg with at least 50 hPa of weather margin. Sea-level-corrected Ecowitt, WeeWX, and calibrated BME/VPD/AQI readings use a sea-level range, following cPyNodus_III semantics. Measurements, history, MQTT payloads, and calibration are unchanged.

Covers initial and live-update rendering, documents the behavior, and updates the version to v0.26.261.7.

Verification

• macOS, Python 3.13.9; isolated host-mode fixture, no broker or direct hardware.
• python3 -m pytest testApparatus/test_display_units.py testApparatus/test_sai_html_gauge_config.py testApparatus/test_dashboard_sensor_row_collapse.py -q: 46 passed.
• python3 -m pytest testApparatus/test_compile_python.py -q: 1 passed.
• npm run validate:pr: 41 passed in local Chromium.
• npm run validate:pr -- tests/pressure-gauges.spec.js: 4 passed after the final live-update fallback fix.
• Reviewed fallback-renderer screenshot; user verified the change.
• git diff --check: passed.

Contributor checklist

• This pull request is focused on one logical change.
• I added or updated tests for behavior changes.
• I updated the canonical documentation when behavior or configuration changed.
• I did not commit credentials, private runtime configuration, databases, or logs.
• I preserved compatibility-sensitive MQTT, settings, switch identity, and persistence behavior, or documented an intentional break.

Maintainer verification

• Required remote checks pass (Python 3.11/3.13 compile and full regression suite with coverage floor).
• npm run validate:pr passes on a trusted host when the change can affect rendered UI behavior.
• Hardware-, broker-, onboarding-, and platform-specific behavior not covered remotely is recorded below.

Residual risk or unverified areas

Physical sensors, live MQTT brokers, onboarding, Raspberry Pi GPIO, Windows, and Linux runtime behavior were not exercised locally. GaugeJS configuration is checked with a test double; the built-in canvas fallback is exercised and visually reviewed. Refresh the dashboard after changing altitude.