⚡ Bolt: [performance improvement] Concurrent email sending via Promise.all

[Snigdh41]

What: Refactored the Resend email API calls in the contact worker to execute concurrently using Promise.all() instead of sequentially.
Why: Sequential external HTTP requests in Cloudflare Workers block execution and accumulate latency. Since the notification email and auto-reply email are independent, they can be sent at the same time.
Impact: Reduces the external API latency overhead by ~50%, leading to a significantly faster overall worker response time for the user submitting the form.
Measurement: Measure the total execution time of the /contact API endpoint before and after the change; expect the duration of the email-sending phase to roughly halve.

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PR created automatically by Jules for task 16726752673921251666 started by @Snigdh41

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