fix: correct Chicago follow-up day boundaries

[JonasFocus]

Summary

Fix the CRM overview's today cutoff on Chicago daylight saving transition days.

Changes

• Extract a pure calendar-day boundary helper that can be tested without authentication.
• Find the next local date boundary instead of adding a fixed 24 hours.
• Add 12 regression tests for both DST transitions, the repeated fall hour, ordinary dates, milliseconds, midnight, and year rollover.

Why

On March 8, 2026 at 00:30 in Chicago, the old cutoff extended to 01:00 the next day. On November 1 at 00:30, it stopped at 23:00 the same day. Follow-ups were therefore included or omitted from today incorrectly.

Testing

• Tested locally on Node 24.19.0
• All 30 tests pass, including the existing 18 tests
• Added regression tests, with four failures reproduced before the fix
• Lint, typecheck, and production build pass

Notes

The existing query ranges remain unchanged. Today includes due times from now up to, but excluding, next local midnight. The attention list includes overdue follow-ups and follow-ups before that cutoff. No live database was accessed.

[vercel]

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Project	Deployment	Actions	Updated
jonas-dev	Ready	Preview	Sep 29, 2026 7:06pm UTC

[JonasFocus]

Reviewed head 51a6fdf3d394cb31877cd8addf101d3c494c07c8.

No blocking findings. The fix preserves the overview query predicates and uses the next local calendar boundary on both DST transitions, including both occurrences of the repeated fall hour.

Validation: 30 tests, lint, typecheck, the getOverview caller probe, and 7,308 independent boundary probes passed. CI and the Vercel preview also passed for this head.