Summary

Document the stream processing framework including stream aggregator, aggregation processor, time series management, and ring buffer for real-time metric aggregation.

Parent Issue

Part of: [EPIC] docs: Address documentation gaps across all ecosystem systems (kcenon/common_system#325)

Background (Why)

monitoring_system includes a stream processing subsystem at include/kcenon/monitoring/utils/ that enables real-time metric aggregation, but it has no dedicated documentation. Users cannot discover or configure windowed aggregation, time series buffering, or statistical processing.

Source files:

• include/kcenon/monitoring/utils/stream_aggregator.h — Real-time stream aggregation
• include/kcenon/monitoring/utils/aggregation_processor.h — Aggregation pipeline
• include/kcenon/monitoring/utils/time_series.h — Time series data management
• include/kcenon/monitoring/utils/time_series_buffer.h — Buffered time series
• include/kcenon/monitoring/utils/statistics.h — Statistical computation
• include/kcenon/monitoring/utils/ring_buffer.h — Fixed-size circular buffer
• include/kcenon/monitoring/utils/metric_storage.h — Metric persistence

Scope (What)

Create docs/guides/STREAM_PROCESSING.md covering:

1. Stream Processing Architecture

• Data pipeline: raw metrics → aggregation → storage/export
• Windowing strategies (tumbling, sliding, session)
• Buffer management and memory control

2. Stream Aggregator

• Real-time aggregation operations (sum, avg, min, max, percentiles)
• Window configuration
• Flush triggers and intervals

3. Time Series Management

• Time series data model
• Retention and downsampling
• Query patterns

4. Ring Buffer

• Fixed-size circular buffer for bounded memory
• Thread safety guarantees
• Configuration and sizing

5. Statistics Engine

• Available statistical functions
• Online vs batch computation
• Accuracy guarantees

6. Usage Examples

• Real-time request latency aggregation
• System resource trend analysis
• Custom aggregation pipeline

Acceptance Criteria

• All 7 stream processing components documented
• Windowing strategies explained
• Memory management patterns documented
• At least 3 usage examples