Optimize sequential namespace search using asyncio.gather

[ishaanxgupta]

What: Optimized sequential namespace searches in _search_symbols and _search_files in src/pipelines/code_retrieval.py using asyncio.gather.

Why: The codebase iterated over self.repos and awaited a separate asynchronous namespace search sequentially for each repository. This caused latency to scale linearly with the number of repositories searched. Using asyncio.gather executes these searches concurrently.

Impact: Significant reduction in latency for multi-repository code queries.

Measurement: In local mocked benchmarking with an artificial 100ms latency per namespace search and 10 configured repositories, query times dropped from 2.01 seconds to 0.20 seconds per call.

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PR created automatically by Jules for task 6874361935615458554 started by @ishaanxgupta

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[ishaanxgupta]

lgtm @ved015 have a look

[ved015]

lgtm please merge it