⚡ Bolt: [performance improvement] Prevent LLM API rate limits during parallel extraction

[ishaanxgupta]

💡 What: Added concurrency control using `asyncio.Semaphore(5)` to bound the number of concurrent LLM calls during batched extractions in `_node_extract_profile`, `_node_extract_temporal`, `_node_extract_code`, and `_node_extract_snippet`.
🎯 Why: While `asyncio.gather` was used to parallelize sub-queries across the LLM, doing so unbounded could cause API rate limiting errors when a user query generates a large number of profile/temporal/code/snippet sub-queries. Bounding concurrency balances throughput and stability.
📊 Measured Improvement: The underlying performance logic (using `asyncio.gather`) is preserved and effectively optimized by preventing failures under heavy load. A benchmark simulating network API latency showed no degradation for small sets of queries, while effectively capping concurrency at 5 requests at a time to keep it robust against rate limit crashes.

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PR created automatically by Jules for task 8918555165628498996 started by @ishaanxgupta

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