Suppress Someday marks inside the Someday view

[MaplumeX]

Summary

The dashed-border / gray-dashed treatment (Things 3 style) that flags Someday items is meaningless on the Someday page itself, where every item is a Someday item. This change introduces a small context so that subtree can opt out of the mark.

Changes

• New somedayMark.ts — adds SomedayMarkContext (defaults to true) and a useSomedayMark() hook, documenting that the mark is on by default and can be disabled for subtrees where it carries no signal.
• TaskCheckbox — only applies border-dashed when someday && somedayMark, so callers can turn the mark off.
• ProjectProgressRing — only uses the dashed outer ring / muted gray styling when somedayMark is enabled; behavior elsewhere is unchanged.
• Someday page — wraps the feed list in SomedayMarkContext.Provider value={false} so entries render with normal styling.

Tests

• Added a TaskCheckbox test asserting the dashed border is skipped when the context is false.
• Existing tests are unaffected, since the context defaults to true.

Notes

No API or data changes; the flag is purely presentational and scoped to the component tree.