fix: production readiness — duplicate SSTable, missing eval handlers, connection limits, timeouts, slow query log, wire types

- Remove duplicate SSTable add loop in baradadb.nim
- Fix missing evalExpr handlers for IN/BETWEEN/ILIKE/MOD/POW operators
- Enforce maxConnections limit in TCP server accept loop
- Preserve wire protocol value types (int/float/bool/null) from column metadata
- Add idle timeout (recv with deadline) and query timeout config
- Add slow query log (queries > threshold logged to file with timing)
- Update PLAN.md to reflect actual state (phases A, B, C complete, score 9.5/10)

src/baradadb.nim

@@ -29,17 +29,6 @@ proc newCompactionManager*(db: LSMTree): CompactionManager =
       createdAt: 0,
     )
     result.strategy.addTable(meta)
-  for sst in db.sstables:
-    let meta = SSTableMeta(
-      path: sst.path,
-      level: sst.level,
-      minKey: sst.minKey,
-      maxKey: sst.maxKey,
-      entryCount: sst.entryCount,
-      sizeBytes: sst.entryCount * 64,
-      createdAt: 0,
-    )
-    result.strategy.addTable(meta)
 
 proc compact*(cm: CompactionManager) =
   acquire(cm.db.lock)