Invoice Sent/Open/View Status with Date & Time Tracking

We need read/seen status for all outbound invoices. Each invoice should clearly show:

• Sent (sealed envelope) — the email was successfully sent.

• Email Opened (open envelope) — the recipient opened the invoice email.

• Invoice Viewed (eye) — the invoice page itself was opened.

Each status must include date + time and appear both on the invoice list and the invoice detail/timeline.