Fix FileNotFoundError for /usr/local/CyberPanel/bin/python on fresh install

- install.py: only use system Python or /usr/local/CyberCP/bin/python for migrations;
  never add /usr/local/CyberPanel paths to candidate list (often missing on fresh install)
- install_utils.py: if command uses /usr/local/CyberPanel/bin/python and it does not
  exist, substitute /usr/bin/python3 and force shell=True so old/cached install.py
  also works without failing

install/install.py

@@ -3367,19 +3367,16 @@ password="%s"
         if not self.ensureVirtualEnvironmentSetup():
             logging.InstallLog.writeToFile("WARNING: No venv found; will try system Python", 1)
 
-        # Find Python: try system Python first so we never use missing /usr/local/CyberPanel/bin/python
-        # (venv may not exist yet; /usr/local/CyberPanel is legacy and often missing on fresh install)
+        # Find Python: use only system Python or CyberCP venv (never /usr/local/CyberPanel - often missing on fresh install)
         python_paths = [
             "/usr/bin/python3",
             "/usr/local/bin/python3",
         ]
         if sys.executable and sys.executable not in python_paths:
             python_paths.append(sys.executable)
-        python_paths.extend([
-            "/usr/local/CyberCP/bin/python",
-            "/usr/local/CyberPanel/bin/python",
-            "/usr/local/CyberPanel-venv/bin/python",
-        ])
+        # Only add venv if it exists (avoid FileNotFoundError)
+        if os.path.isfile("/usr/local/CyberCP/bin/python"):
+            python_paths.append("/usr/local/CyberCP/bin/python")
 
         python_path = None
         for path in python_paths:

install/install_utils.py

@@ -573,6 +573,15 @@ def call(command, distro, bracket, message, log=0, do_exit=0, code=os.EX_OK, she
             command = re.sub(r'^(\s*)(?:sudo\s+)?(mysql|mariadb)(\s)', r'\g<1>' + mysql_bin + r'\g<3>', command, count=1)
         shell = True
 
+    # CRITICAL: /usr/local/CyberPanel/bin/python often missing on fresh install; use system Python for manage.py
+    if '/usr/local/CyberPanel/bin/python' in command and not os.path.isfile('/usr/local/CyberPanel/bin/python'):
+        fallback = '/usr/bin/python3'
+        if not os.path.isfile(fallback):
+            fallback = '/usr/local/bin/python3'
+        if os.path.isfile(fallback):
+            command = command.replace('/usr/local/CyberPanel/bin/python', fallback, 1)
+        shell = True  # ensure shell so path with spaces is not split
+
     finalMessage = 'Running: %s' % (message)
     stdOut(finalMessage, log)
     count = 0