fix(twincat): accept TwinCAT 2 leading-dot globals in TwinCATSymbolPath (ignitionoee 0.19.1)

A TC2 global is named with ONE leading dot (.OPC_HEARTBEAT) and the PLC
requires it (SYM_HNDBYNAME answers 0x710 without it). TryParse rejected the
dot, so the driver fell back to the raw string and lost bit-index parsing:
.X.WORD.3 went to ADS verbatim instead of reading .X.WORD and extracting bit 3.
The dot now stays on the root segment and round-trips through ToAdsSymbolName;
.., ., .[1] and .9x stay invalid.

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Cli/Commands/ReadCommand.cs

@@ -14,7 +14,8 @@ public sealed class ReadCommand : TwinCATTagCommandBase
     /// <summary>Gets or sets the TwinCAT symbol path to read.</summary>
     [CommandOption("symbol", 's', Description =
         "Symbol path. Program scope: 'MAIN.bStart'. Global: 'GVL.Counter'. " +
-        "Nested UDT member: 'Motor1.Status.Running'. Array element: 'Recipe[3]'.",
+        "Nested UDT member: 'Motor1.Status.Running'. Array element: 'Recipe[3]'. " +
+        "TwinCAT 2 global (keep its leading dot): '.OPC_HEARTBEAT'.",
         IsRequired = true)]
     public string SymbolPath { get; init; } = default!;