fix(web): align command palette navigation

[Uarmagan]

Summary

Fixes the command palette navigation sections so Week, Day, and Now present the same kind of view-switching actions.

Before this change, each view built its own command palette navigation list. That made the palette feel different depending on where you opened it: Week did not have a Navigation section, Day mixed create/edit actions into Navigation, and Now was missing Today while also mixing reminder editing into Navigation.

This PR:

• adds one shared navigation item builder for the view-switching commands
• gives Week, Day, and Now consistent Navigation sections
• keeps create/edit/reminder actions under Common Tasks instead of Navigation
• adds a real Now t shortcut for “Go to Today,” matching the command palette label and shortcut help

Closes #1808

Validation

• Reproduced the original inconsistency in Browser before changing code.
• Re-tested in Browser after the fix:
  • Week palette shows Now, Day, and Today under Navigation
  • Day palette shows Now, Week, and Today under Navigation
  • Now palette shows Day, Week, and Today under Navigation
  • Week → Now works from the palette
  • Now → Today works from the palette
  • Now t shortcut goes to today
  • Day → Week works from the palette
• bun test src/common/constants/navigation.cmd.constants.test.ts src/views/Now/shortcuts/useNowShortcuts.test.tsx src/common/utils/shortcut/data/shortcuts.data.test.ts from packages/web
• bun type-check
• bun lint
• git diff --check

Note: bun test:web currently hits a repeatable Bun segmentation fault while starting src/common/hooks/useLogoutCmdItems.test.ts. That test passes when run directly, and the full run progressed cleanly otherwise, so I treated it as a Bun/runtime issue rather than a regression from this PR.