Description

On startup, the TUI always fires refresh_data() immediately even if the Next.js app's snapshots are only seconds old. Instead, read refreshedAt from each snapshot and compute how much of the TTL has already elapsed, then wait only the remaining time before the first refresh.

For example: if a source has a 5-minute TTL and its snapshot is 4 minutes old, the TUI should wait ~1 minute before its first fetch, not 5 minutes (or 0).

Implementation:

• After the initial fetch_sources() call, extract min(refreshedAt) or per-source refreshedAt from snapshots
• Compute remaining = refresh_interval - (now - refreshedAt)
• Schedule the first repeating timer to fire after max(0, remaining) seconds
• Fall back to immediate refresh if no snapshots exist

Acceptance Criteria

• #1 Restarting TUI with fresh data does not immediately re-fetch all sources
• #2 Restarting TUI with stale data fetches immediately
• #3 Logic degrades gracefully when refreshedAt is missing from snapshot