Find Maia UCI binary from deploy venv

deploy/systemd/maia-engine.service

@@ -13,6 +13,7 @@ Environment=MAIA_DEVICE=cpu
 Environment=MAIA_USE_AMP=false
 Environment=HF_HOME=/root/blog-backend/.cache/huggingface
 Environment=PYTHONUNBUFFERED=1
+Environment=PATH=/root/blog-backend/maia-engine-venv/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 ExecStart=/root/blog-backend/maia-engine-venv/bin/python -m uvicorn app.main:app --host 127.0.0.1 --port 8000
 Restart=always
 RestartSec=5

maia-engine/app/main.py

@@ -1,7 +1,10 @@
 import os
+import shutil
 import subprocess
+import sys
 import threading
 from datetime import datetime, timezone
+from pathlib import Path
 
 import chess
 import chess.engine
@@ -37,9 +40,22 @@ def model_alias(model: str) -> str:
     return f"maia3-{model}"
 
 
+def engine_executable() -> str:
+    executable_name = "maia3-uci.exe" if os.name == "nt" else "maia3-uci"
+    venv_executable = Path(sys.executable).with_name(executable_name)
+    if venv_executable.exists():
+        return str(venv_executable)
+
+    path_executable = shutil.which("maia3-uci")
+    if path_executable:
+        return path_executable
+
+    return "maia3-uci"
+
+
 def engine_command(model: str) -> list[str]:
     command = [
-        "maia3-uci",
+        engine_executable(),
         "--model",
         model_alias(model),
         "--use-uci-history",