Release v1.4 — Warm ivory theme, member avatars, code cleanup

[danialkhilji]

Summary

• Warm ivory theme with dark floating nav bar, custom SVG prayer icons, night sky weather variants
• Member avatar upload with photo display across all pages
• Unified add/edit modals (10 files → 5)
• Extracted shared components and constants (GripIcon, ColourPicker, MemberDot, calendarUtils, INPUT_STYLE, TAP_SPRING)
• Extracted backend shared utilities (verify_member_exists, reorder_items, ReorderRequest, scheduler helper)
• Deduplicated schemas, standardized modal state naming, fixed members router
• Split README into landing page + deployment/development guides
• Added contributing guide, screenshots, and complete v1.4 changelog
• Fixed 8 bugs: rotation reset, cleanup field, calendar month, Feb 29 birthdays, stale closure, weekly filter, birthday cache, prayer alignment
• 135 backend tests, zero TypeScript errors, zero ruff lint errors

Test plan

• All 135 backend tests pass
• TypeScript compiles cleanly
• Frontend builds successfully
• Ruff lint passes with zero errors
• Visual QA on iPad and iPhone
• Tag v1.4 on main after merge