docs: expand README and documentation for production release

- Update README.md status from 'educational proof-of-concept' to 'production-ready'
- Fix binary size: 286KB -> 3.3MB
- Update test count: 162/35 -> 262/56
- Add sections: benchmarks, Docker, clients, security, config, monitoring, backup, cross-modal queries, troubleshooting
- Expand project structure with all 49 modules and ~14,100 LOC
- Add 10 new docs: performance, deployment, configuration, clients, security, monitoring, backup, crossmodal, troubleshooting, changelog
- Expand docs/en: architecture, baraql, installation, protocol
- Update docs/bg: architecture, installation
- Update docs/index.md with new links
- Update .gitignore for __pycache__, rust/target, nim binaries

.gitignore

@@ -26,3 +26,14 @@ Thumbs.db
 
 # External references
 GEL/
+
+# Python
+__pycache__/
+*.pyc
+
+# Rust
+clients/rust/target/
+
+# Nim compiled binaries
+clients/nim/src/baradb/client
+src/barabadb/storage/compaction