fix: re-scan updates services on existing pending devices instead of skipping

backend/app/services/scanner.py

@@ -115,16 +115,21 @@ async def run_scan(ranges: list[str], db: AsyncSession, run_id: str) -> None:
                 services = fingerprint_ports(host["open_ports"])
                 suggested_type = suggest_node_type(host["open_ports"])
 
-                # Skip if already pending (by IP)
-                existing = await db.execute(
+                # Update existing pending device or create a new one
+                existing_result = await db.execute(
                     select(PendingDevice).where(
                         PendingDevice.ip == host["ip"],
                         PendingDevice.status == "pending",
                     )
                 )
-                if existing.scalar_one_or_none():
-                    continue
-
+                existing = existing_result.scalar_one_or_none()
+                if existing:
+                    existing.mac = host.get("mac") or existing.mac
+                    existing.hostname = host.get("hostname") or existing.hostname
+                    existing.os = host.get("os") or existing.os
+                    existing.services = services
+                    existing.suggested_type = suggested_type
+                else:
                     device = PendingDevice(
                         ip=host["ip"],
                         mac=host.get("mac"),