feat: Implement real streaming integrations for Kafka, Pub/Sub, and Kinesis

This commit implements production-ready streaming integrations for all three major streaming backends with feature flags:

**🚀 AWS Kinesis Streaming Integration (`kinesis` feature)**
- Production-ready KinesisProcessor using official AWS SDK for Rust
- Support for explicit AWS credentials and default credential chain (IAM roles, environment, profiles)
- Real-time record publishing with automatic partition key generation
- Comprehensive stream health checks using DescribeStream API with stream status validation
- Detailed delivery tracking with sequence numbers, shard IDs, and timing metrics
- Robust error handling and proper AWS region configuration

**☁️ Google Cloud Pub/Sub Streaming Integration (`google-pubsub` feature)**
- Production-ready PubSubProcessor using official Google Cloud Pub/Sub SDK
- Support for service account JSON credentials and Application Default Credentials (ADC)
- Real-time message publishing with message attributes for event metadata and correlation
- Ordering key support for maintaining message order within partitions
- Comprehensive error handling and health checks

**📡 Apache Kafka Streaming Integration (`kafka` feature)**
- Production-ready KafkaProcessor using rdkafka crate
- Configurable Kafka producer settings (bootstrap servers, compression, acks, retries, batch size)
- Real-time message delivery with partition key support and custom headers
- Comprehensive health checks using Kafka cluster metadata fetching and topic validation
- Graceful shutdown with message flushing to ensure no data loss

**Shared Features**
- Feature-gated implementations that gracefully degrade when features are disabled
- Comprehensive error handling with detailed error messages for debugging
- Message delivery tracking with success/failure reporting and timing metrics
- Health checks and graceful shutdown capabilities for all backends
- Full backward compatibility with existing placeholder implementations

This replaces the placeholder implementations with real SDK integrations while maintaining the same API surface and providing fallback behavior when features are disabled.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: CodingAnarchy

CHANGELOG.md

@@ -7,6 +7,40 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- **📡 Kafka Streaming Integration**
+  - Added real Apache Kafka integration with `kafka` feature flag using `rdkafka` crate
+  - Implemented production-ready `KafkaProcessor` with real Kafka producer functionality
+  - Support for configurable Kafka producer settings (bootstrap servers, compression, acks, retries, batch size, etc.)
+  - Real-time message delivery with partition key support for proper message distribution
+  - Custom message headers support for tracing, metadata, and event correlation
+  - Comprehensive health checks using Kafka cluster metadata fetching and topic validation
+  - Graceful shutdown with message flushing to ensure no data loss
+  - Producer statistics and metrics reporting for monitoring and debugging
+  - Configurable timeouts for health checks and message delivery operations
+
+- **☁️ Google Cloud Pub/Sub Streaming Integration**
+  - Added real Google Cloud Pub/Sub integration with `google-pubsub` feature flag
+  - Implemented production-ready `PubSubProcessor` using official Google Cloud Pub/Sub SDK
+  - Support for both service account JSON credentials and Application Default Credentials (ADC)
+  - Real-time message publishing with message attributes for event metadata and correlation
+  - Ordering key support for maintaining message order within partitions
+  - Comprehensive error handling with detailed error messages for debugging
+  - Health checks and graceful shutdown capabilities
+  - Message delivery tracking with success/failure reporting and timing metrics
+  - Feature-gated implementation that gracefully degrades when feature is disabled
+
+- **🚀 AWS Kinesis Streaming Integration**
+  - Added real AWS Kinesis Data Streams integration with `kinesis` feature flag
+  - Implemented production-ready `KinesisProcessor` using official AWS SDK for Rust
+  - Support for both explicit AWS credentials and default credential chain (IAM roles, environment variables, profiles)
+  - Real-time record publishing with automatic partition key generation and custom partitioning support
+  - Comprehensive stream health checks using `DescribeStream` API with stream status validation
+  - Detailed delivery tracking with sequence numbers, shard IDs, and timing metrics
+  - Robust error handling with retry logic and detailed error reporting
+  - Feature-gated implementation that gracefully degrades when feature is disabled
+  - Proper AWS region configuration and credential management
+
 ## [1.14.0] - 2025-07-17
 
 ### Added

Cargo.toml

@@ -109,6 +109,10 @@ google-cloud-auth = { version = "0.4", optional = true }
 vaultrs = { version = "0.7", optional = true }
 azure_security_keyvault = { version = "0.20", optional = true }
 azure_identity = { version = "0.20", optional = true }
+rdkafka = { version = "0.36", optional = true }
+google-cloud-pubsub = { version = "0.25", optional = true }
+google-cloud-googleapis = { version = "0.13", optional = true }
+aws-sdk-kinesis = { version = "1.0", optional = true }
 
 [features]
 default = ["metrics", "alerting", "webhooks"]
@@ -122,6 +126,9 @@ aws-kms = ["aws-sdk-kms", "aws-config"]
 gcp-kms = ["google-cloud-kms", "google-cloud-auth"]
 vault-kms = ["vaultrs"]
 azure-kv = ["azure_security_keyvault", "azure_identity"]
+kafka = ["rdkafka"]
+google-pubsub = ["google-cloud-pubsub", "google-cloud-auth", "google-cloud-googleapis"]
+kinesis = ["aws-sdk-kinesis", "aws-config"]
 tracing = ["opentelemetry", "opentelemetry_sdk", "opentelemetry-otlp", "tracing-opentelemetry"]
 test = []