Refresh Decodex UI clocks

[yvette-carlisle]

Summary

• add a native app local clock so reset countdowns and operator age labels update without waiting for account data refreshes
• add a dashboard local clock for relative/reset labels while explicitly skipping account API refreshes on clock-only ticks
• add regression coverage for reset countdowns crossing into due state

Validation

• swift test --package-path apps/decodex-app
• dashboard script syntax check + local tick skips account refresh assertion
• cargo make fmt-check
• git diff --check
• cargo check -p decodex --bin decodex

API cadence

The dashboard local clock calls renderDashboardState with refreshAccounts: false, so it does not increase /api/accounts, Linear, or GitHub polling frequency.