fix: preserve flushed buffers during stop_streaming

[cucuwritescode]

summary

fixes data loss issue where flushed buffers in _processed_data_msg_queue were discarded when stop_streaming() was called causing users to lose final data chunks.

issue

when stop_streaming() was called, the _processed_data_msg_queue was cleared by creating a new empty queue,
discarding any remaining messages that hadn't been processed yet. This resulted in users losing their final data
chunks.

solution

before clearing the queue, safely drain all remaining messages and add them to the appropriate
streaming_buffers_queue so users can access their complete data. The implementation includes comprehensive error
handling to ensure robustness.

what was changed

• added buffer collection logic in _async_stop_streaming() before queue clearing
• implemented triple-layer error handling for max stability
• preserved all existing functionality with graceful fallback behaviour

tests

• verifief preservation of data with test scenarios
• confirmed error handling with corrupted messages
• validated no breaking changes to existing functionality