⚡ Bolt: [performance improvement] Avoid mime.ParseMediaType in hot path

[callmeradical]

💡 What: Replaced mime.ParseMediaType with strings.HasPrefix and strings.ToLower in the hot path for parsing HTTP response content type inside cmd/sergeant-mcp-client/proxy.go.
🎯 Why: mime.ParseMediaType allocates a map for media type parameters and parses the full string, creating unnecessary memory overhead and garbage collection pressure in hot paths.
📊 Impact: Reduces memory allocations and CPU overhead during streaming or high-volume JSON-RPC request proxying.
🔬 Measurement: Run the test suite (go test ./...) and optionally profile the application during high load to verify reduced memory allocations in writeResponse.

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PR created automatically by Jules for task 3485981920556637694 started by @callmeradical

[google-labs-jules]

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[callmeradical]

Closing as a duplicate/superseded Jules proposal. The canonical implementation is merged in #316.

[google-labs-jules]

Closing as a duplicate/superseded Jules proposal. The canonical implementation is merged in #316.

Understood. Acknowledging that this work is now obsolete and stopping work on this task.