⚡ Bolt: Optimize content-type prefix matching to avoid allocation

[callmeradical]

💡 What: Replaced strings.HasPrefix(strings.ToLower(resp.contentType), "text/event-stream") with a zero-allocation approach using strings.EqualFold.
🎯 Why: strings.ToLower forces a memory allocation on the hot path of handling every HTTP response in the proxy. By using slicing and strings.EqualFold, we achieve the same case-insensitive prefix matching without allocating memory.
📊 Impact: Eliminates a memory allocation per proxy response, reducing GC pressure and improving latency.
🔬 Measurement: Review the code to verify the elimination of strings.ToLower, and run go test ./... to ensure correctness.

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PR created automatically by Jules for task 3591243859574229893 started by @callmeradical

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