Coordinate calendar and page-chrome colors to a single hue

[brianglass]

Summary

• The calendar's normal/fast day-cell colors, the topbar, the date-section panel gradient, and the body background gradient had each drifted to slightly different hues (up to 5-7 degrees apart) despite being intended as one cohesive warm-parchment palette.
• Rebased all of them to the same 40-degree hue (varying only lightness/saturation), then lightened the calendar cells and darkened the day-of-week header text (Sun/Mon/Tue/...) for better legibility within the new palette.

Test plan

• Verified visually in-browser across the readings page (topbar, date section) and calendar page (day cells, fast-day cells, hover states, day-name header) at multiple months
• Full test suite — this is a CSS-only color change with no behavioral impact; not run locally, CI will cover it

🤖 Generated with Claude Code

https://claude.ai/code/session_01Hf6j2xXQXywHVh3HAVRxB3