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/baradadb.nim

@@ -1,15 +1,78 @@
 ## BaraDB — Multimodal Database Engine
 ## Main entry point
 import std/asyncdispatch
+import std/threadpool
+import std/locks
 import barabadb/core/server
+import barabadb/core/httpserver
 import barabadb/core/config
+import barabadb/storage/lsm
+import barabadb/storage/compaction
+
+type
+  CompactionManager* = ref object
+    db*: LSMTree
+    strategy*: compaction.CompactionStrategy
+
+proc newCompactionManager*(db: LSMTree): CompactionManager =
+  result = CompactionManager(db: db, strategy: compaction.newCompactionStrategy(db.dir))
+  for sst in db.sstables:
+    let meta = compaction.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)
+  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)
+  defer: release(cm.db.lock)
+  for level in 0 ..< compaction.MaxLevel:
+    if cm.strategy.needsCompaction(level):
+      discard cm.strategy.compact(level)
+
+proc startCompactionLoop*(cm: CompactionManager, intervalMs: int = 60000) {.async.} =
+  while true:
+    await sleepAsync(intervalMs)
+    cm.compact()
+
+proc runTcpServer(config: BaraConfig) {.async.} =
+  echo "BaraDB TCP listening on ", config.address, ":", config.port
+  var server = newServer(config)
+  await server.run()
 
 proc main() =
   let config = loadConfig()
   echo "BaraDB v0.1.0 — Multimodal Database Engine"
-  echo "Listening on ", config.address, ":", config.port
-  var server = newServer(config)
-  waitFor server.run()
+
+  # Start HTTP server (blocking, multi-threaded via hunos) in background thread
+  var httpServer = newHttpServer(config)
+  spawn httpServer.run(config.port + 440)  # HTTP port = TCP port + 440
+
+  # Start background compaction loop
+  let cm = newCompactionManager(httpServer.db)
+  asyncCheck cm.startCompactionLoop()
+
+  # Start TCP wire protocol server on main thread with async event loop
+  waitFor runTcpServer(config)
+
+  # Shutdown
+  httpServer.stop()
 
 when isMainModule:
   main()