Update someday shortcuts to use `SHIFT` prefix

[tyler-dane]

Priority

None

Feature Description

Currently the week view support these shortcuts:
w creates a someday week event
m creates a someday month event.

We should change it to

SHIFT + w and SHIFT + m respectively.

Use Case

This lets us reserve the w and m keys for the views (Week view, (future) Month View).

It also reinforces the SHIFT <-> sidebar association, which we've already established with the SHIFT + 1 shortcut that swaps sidebar views.

Additional Context

Put on hold to give us more time to experiment with how it feels currently, with the normal w and m shortcuts.