waybackTimestampToISO silently returns current date for malformed input

[oritwoen]

In src/utils/_utils.ts:65-69:

export function waybackTimestampToISO(timestamp: string): string {
  return timestamp.length >= 14 
    ? \`\${timestamp.slice(0,4)}-...\`
    : new Date().toISOString()
}

When the timestamp is shorter than 14 characters (or empty), the function returns today's date. This is used by both the Wayback and CommonCrawl providers to set ArchivedPage.timestamp.

The problem: an archive from 2015 with a truncated timestamp silently gets today's date. The caller has no way to tell the timestamp was fabricated vs. real. For a library whose job is returning historical data, this quietly corrupts the one field users depend on most.

Options worth considering:

• Return a distinguishable sentinel (empty string, or an explicit null with a type change)
• Pad shorter timestamps with zeros so 20220101 → 2022-01-01T00:00:00Z instead of 2026
• Log a warning via consola so the caller at least sees it