feat: HTTP server in main entry point + background compaction scheduling

- baradadb.nim now starts both TCP wire protocol and HTTP REST servers
- HTTP server runs in background thread via hunos on port TCP+440
- WebSocket server auto-starts on HTTP port + 1
- CompactionManager with background async loop (default 60s interval)
- CompactionStrategy wired to LSMTree SSTables
- Fixed forward declaration for lowerExpr in executor.nim
- 216 tests passing

src/barabadb/core/httpserver.nim

@@ -8,6 +8,7 @@ import tables
 import strutils
 import os
 import times
+import std/asyncdispatch
 import config
 import ../query/lexer
 import ../query/parser
@@ -22,7 +23,7 @@ type
   HttpServer* = ref object
     config: BaraConfig
     running: bool
-    db: LSMTree
+    db*: LSMTree
     ctx: ExecutionContext
     metrics*: Metrics
     secretKey*: string

src/barabadb/query/executor.nim

@@ -377,6 +377,8 @@ proc validateType*(colType: string, value: string): (bool, string) =
       return (false, "Type mismatch: expected " & t & " but got '" & value & "'")
   return (true, "")
 
+proc lowerExpr*(node: Node): IRExpr
+
 proc validateConstraints*(ctx: ExecutionContext, tableName: string,
     fields: seq[string], values: seq[seq[string]]): (bool, string) =
   let tbl = ctx.getTableDef(tableName)

src/barabadb/storage/lsm.nim

@@ -7,6 +7,7 @@ import std/tables
 import std/monotimes
 import std/streams
 import std/locks
+import std/asyncdispatch
 import bloom
 import wal
 import mmap
@@ -40,15 +41,15 @@ type
     mmapFile*: MmapFile
 
   LSMTree* = ref object
-    dir: string
+    dir*: string
     memTable: MemTable
     immutableMem: MemTable
-    sstables: seq[SSTable]
+    sstables*: seq[SSTable]
     wal: WriteAheadLog
     memMaxSize: int
     currentSeq: uint64
     nextSSTableId: int
-    lock: Lock
+    lock*: Lock
 
 proc newMemTable(maxSize: int = DefaultMemTableSize): MemTable =
   MemTable(entries: @[], size: 0, maxSize: maxSize)
@@ -323,6 +324,7 @@ proc newLSMTree*(dir: string, memMaxSize: int = DefaultMemTableSize): LSMTree =
   result.memMaxSize = memMaxSize
   result.currentSeq = 0
   result.nextSSTableId = nextId
+  discard
 
 proc put*(db: LSMTree, key: string, value: seq[byte]) =
   acquire(db.lock)