[2] [TASK] [Backend] [Core] Document RawDataBuffer as a dedicated component

[R4R35]

Description

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The current async infrastructure uses a bounded ThreadPoolTaskExecutor queue of 100 as an implicit buffer. This task makes the RawDataBuffer explicit as a documented component, as required by the architecture docs.

Scope

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• Add comments/documentation in AsyncConfig explaining the queue as a RawDataBuffer
• Expose queue capacity and thread pool sizes as configurable properties in application.properties
• Log a warning when the queue is near capacity

Done When

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• Queue capacity is configurable via application.properties
• A warning is logged when queue reaches 80% capacity
• AsyncConfig is clearly documented explaining the buffer role

Priority

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• 🟢 Low