Move modules into es24n/ subfolder

Keeps the repo root clean with es24n_conf.py as the sole entry point.
All supporting modules (ui, serial_port, models, redfish, workflow_*)
now live in es24n/. The entry point adds es24n/ to sys.path at startup
so inter-module imports within the package remain unchanged.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

es24n_conf.py

@@ -15,9 +15,12 @@ All source files must be present in the same directory:
     workflow_serial.py, workflow_firmware.py
 """
 
+import os
 import sys
 import time
 
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), "es24n"))
+
 from ui import _c, C, banner, draw_box, ok, warn, prompt
 from workflow_firmware import firmware_update_workflow
 from workflow_serial import configure_shelf