⚡ Bolt: Concurrent email sending via Promise.all

[Snigdh41]

💡 What: Replaced sequential email sending requests with concurrent execution using Promise.all() in the contact API worker.
🎯 Why: Making multiple external HTTP requests to Resend sequentially accumulates network latency, increasing the total response time of the Cloudflare Worker and degrading user experience.
📊 Impact: Reduces the overall execution time of the contact API handler by approximately the duration of one API request (roughly 50% faster email sending phase).
🔬 Measurement: Verify the improvement by measuring the time taken for the /contact API endpoint to respond before and after the change; the total time should be noticeably shorter as the requests execute in parallel.

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PR created automatically by Jules for task 11794830171753936964 started by @Snigdh41

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