Make audit log end dates exclusive

[yummybomb]

Summary

• preserve date-only --end values as the exclusive boundary sent to the API
• remove the no-longer-needed date-only parsing marker
• clarify the CLI help text and cover the boundary with a regression test

Testing

• make test
• make build
• not run: make lint (golangci-lint is not installed)

---

Note

Medium Risk
Changes CLI time-window semantics for date-only --end, which can shrink results for scripts that relied on inclusive end-of-day behavior.

Overview
audit-logs search now sends --end to the API as an exclusive boundary instead of extending date-only values by 24 hours so the whole calendar day was included.

parseAuditLogTime no longer returns a dateOnly flag; date strings like 2026-07-01 are passed through as midnight UTC on that date. The --end flag help text now documents exclusivity, and the regression test asserts a window from 2026-06-30 through exclusive 2026-07-01 rather than treating same-day start/end as a full day.

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