feat: add bounded kafka ingestion pipeline

README.md

@@ -21,7 +21,9 @@ FastAPI API
     ↓
 Validation
     ↓
-202 Accepted
+Bounded Async Queue
+    ↓
+Redpanda / cdr.raw
 ```
 
 Infrastructure already available:
@@ -35,7 +37,7 @@ ClickHouse
 └── telecom.cdr_records
 ```
 
-Kafka publishing and worker processing are not connected yet.
+worker processing is not connected yet.
 
 ## Current Features
 
@@ -53,16 +55,27 @@ Kafka publishing and worker processing are not connected yet.
 * FastAPI `GET /health`
 * Structured JSON error responses
 * Unit and API integration tests
+* Bounded asynchronous ingestion queue for backpressure
+* Long-lived asynchronous Kafka producer
+* Kafka delivery acknowledgement before `202 Accepted`
+* `429 Too Many Requests` on ingestion queue saturation
+* `503 Service Unavailable` on Kafka delivery failure
 
 ## Project Structure
 
 ```text
 src/core/
+├── config.py
+│
 ├── api/
+│   ├── __init__.py
+│   ├── kafka_publisher.py
 │   ├── main.py
+│   ├── publisher.py
 │   └── routes.py
 │
 └── domain/
+    ├── __init__.py
     ├── errors.py
     ├── models.py
     ├── normalization.py