⚡ Optimize InsightStore with async RwLock and O(1) storage

[Tuntii]

• 💡 What: Replaced blocking std::sync::RwLock with tokio::sync::RwLock in InMemoryInsightStore. Refactored InsightStore trait to be async using async-trait. Optimized InMemoryInsightStore storage to use VecDeque<Arc<InsightData>> + DashMap<String, Arc<InsightData>> to eliminate O(N) index rebuilding during eviction.
• 🎯 Why: The previous implementation used a blocking lock in async code, causing thread starvation under load. Additionally, the eviction strategy triggered an O(N) index rebuild while holding the write lock, severely limiting throughput.
• 📊 Measured Improvement: In a synthetic benchmark with 50 concurrent tasks storing 1000 insights each:
  • Baseline: ~306s (163 insights/sec)
  • Optimized: ~0.25s (196,969 insights/sec)
  • Speedup: ~1200x throughput improvement.

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PR created automatically by Jules for task 2954011930150916406 started by @Tuntii

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