feat: Add Step 13 - Search System with Apache Solr and Data Persistence

- Implemented search service with Apache Solr instead of Elasticsearch
- Added full-text search, faceted search, and autocomplete capabilities
- Created data indexer for synchronizing data from MongoDB/Kafka to Solr
- Configured external volume mounts for all data services:
  - MongoDB, Redis, Kafka, Zookeeper, MinIO, Solr
  - All data now persists in ./data/ directory
- Added comprehensive search API endpoints
- Created documentation for data persistence and backup strategies

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

Co-Authored-By: Claude <noreply@anthropic.com>

services/search/backend/requirements.txt

@@ -0,0 +1,10 @@
+fastapi==0.109.0
+uvicorn[standard]==0.27.0
+pydantic==2.5.3
+python-dotenv==1.0.0
+pysolr==3.9.0
+httpx==0.25.2
+motor==3.5.1
+pymongo==4.6.1
+aiokafka==0.10.0
+redis==5.0.1