Hide Someday buckets from Day view sidebar

[Uarmagan]

Summary

• hides the Someday week/month buckets from the Day view sidebar
• keeps the Day sidebar calendar, account row, footer controls, and shortcuts overlay
• leaves Week view unchanged so Someday planning still lives there

Why

Day view should feel like the focused daily execution surface. Showing the Someday week/month buckets there made the screen feel like it had multiple task lists, even though those buckets are really event-planning surfaces.

Verification

• NODE_ENV=test TZ=Etc/UTC bun test --preload ./src/tests/web.preload.ts ./src/components/PlannerSidebar/PlannerSidebar.test.tsx
• bun run lint
• bun run type-check
• browser check on /day/2026-05-12, /day date navigation, and /week

Notes

During browser verification, the local dev app still showed existing backend CORS/session-refresh console noise when the backend was not running for this UI-only check.