Refresh user guide screenshots and calendar documentation

[mot-yelraf]

Summary

Refresh the dashboard, Caelus weather forecast, and Biodynamic Calendar screenshots from the live Samhain installation. Streamline the user guide's calendar section and move printing guidance beneath its feature and control descriptions.

Verification

• npm run validate:pr: all 9 tests passed on macOS (Python 3.13.9) using Playwright Chromium and the isolated host fixture.
• git diff --check: passed.
• Rendered Markdown review: heading hierarchy and lists are valid, all images load, and no unparsed Markdown remains.
• Visually reviewed the three live Samhain captures; user confirmed the updates.
• Documentation and image changes only; no runtime code or version change.

Contributor checklist

• This pull request is focused on one logical change.
• Tests for behavior changes: not applicable; no runtime behavior changed.
• Canonical user guide updated.
• No credentials, private runtime configuration, databases, or logs committed.
• Compatibility-sensitive MQTT, settings, switch identity, and persistence behavior preserved.

Maintainer verification

• Required remote checks pass: Python 3.11/3.13 compilation and regression suite.
• npm run validate:pr passes on a trusted host.
• Hardware, broker, onboarding, and platform limits recorded below.

Residual risk or unverified areas

Live values in screenshots are time-specific. Direct hardware, MQTT broker behavior, onboarding, and other runtime platforms were not retested for this documentation-only change. PDF output was not regenerated.