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/models.py

@@ -0,0 +1,23 @@
+"""
+models.py — Shared data classes for ES24N IOM configuration.
+Used by both the serial and network configuration workflows.
+"""
+
+from dataclasses import dataclass, field
+
+
+@dataclass
+class IOMConfig:
+    iom:     str
+    dhcp:    bool = True
+    ip:      str  = ""
+    gateway: str  = ""
+    netmask: str  = ""
+
+
+@dataclass
+class ShelfConfig:
+    device:   str = ""
+    password: str = ""
+    iom1: IOMConfig = field(default_factory=lambda: IOMConfig("IOM1"))
+    iom2: IOMConfig = field(default_factory=lambda: IOMConfig("IOM2"))