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

src/barabadb/storage/recovery.nim

@@ -1,7 +1,6 @@
 ## Crash Recovery — WAL replay with REDO/UNDO
 import std/streams
 import std/os
-import std/tables
 import ../storage/wal
 
 type