feat: complete Phase 3 + new production roadmap for Web/ERP

- Thread-safety: locks in LSMTree and Graph engines
- Raft network transport: async TCP, serialization, heartbeat, 3-node election test
- CI/CD: GitHub Actions workflow
- Cleanup: remove dead code, unused imports, build artifacts
- New PLAN.md targeting production Web/ERP readiness
- 216 tests passing

.gitignore

@@ -2,6 +2,15 @@
 build/
 nimcache/
 nimblecache/
+*.out
+
+# Binaries (compiled test executables)
+tests/test_all
+tests/stress_test
+benchmarks/bench_all
+benchmarks/compare
+clients/nim/tests/test_client
+src/baradadb
 
 # Temp
 *.tmp