[codex] rename calendar view to week view

[Uarmagan]

Summary

This PR renames the main weekly planning surface from Calendar to Week so the code matches what the UI actually represents. The old naming made it easy to confuse the week view with the broader calendar product area, especially around the left sidebar and Someday sections.

The change moves the view folder from packages/web/src/views/Calendar to packages/web/src/views/Week, renames the top-level view to WeekView, and updates the related render test, test helper, and view type filenames. It also renames the Someday sidebar sections from generic week/month section names to SomedayWeekSection and SomedayMonthSection.

All source imports were updated to the new Week paths, including router lazy loading, shared Day/Now references, draft helpers, sidebar code, tests, and utilities. The documentation that maps feature files and runtime flows was updated so future edits point at the new names.

Verification

• bun run type-check
• bun run test:web
• Stale-name search over tracked source and docs for old Calendar view paths/names

Note: bun run lint still reports existing unrelated backend lint issues, so I verified this rename with type-check, the web test suite, and a focused stale-reference sweep.