refactor(driver-ablegacy): extract AbLegacyDriverOptions to .Contracts

Move AbLegacyDriverOptions, AbLegacyDataType enum, and
AbLegacyPlcFamilyProfile (including AbLegacyPlcFamily enum) to a new
Driver.AbLegacy.Contracts sibling project. All three files are zero-dep
after splitting AbLegacyDataTypeExtensions (which uses DriverDataType
from Core.Abstractions) into a new file that stays in the runtime driver.

Drop the doc-comment <see cref="AbLegacyAddress.TryParse"/> reference and
replace with <c>AbLegacyAddress.TryParse</c> per the approved decision.
The PlcFamilies using directive is retained in the contracts project since
both namespaces live there.

The runtime Driver.AbLegacy project gains a ProjectReference to .Contracts;
the .slnx is updated accordingly.

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Contracts/AbLegacyDriverOptions.cs

@@ -0,0 +1,56 @@
+using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.PlcFamilies;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;
+
+/// <summary>
+///     AB Legacy (PCCC) driver configuration. One instance supports N devices (SLC 500 /
+///     MicroLogix / PLC-5 / LogixPccc). Per plan decision #41 AbLegacy ships separately from
+///     AbCip because PCCC's file-based addressing (<c>N7:0</c>) and Logix's symbolic addressing
+///     (<c>Motor1.Speed</c>) pull the abstraction in different directions.
+/// </summary>
+public sealed class AbLegacyDriverOptions
+{
+    /// <summary>Gets or sets the list of PCCC devices to connect to.</summary>
+    public IReadOnlyList<AbLegacyDeviceOptions> Devices { get; init; } = [];
+
+    /// <summary>Gets or sets the list of PCCC tag definitions.</summary>
+    public IReadOnlyList<AbLegacyTagDefinition> Tags { get; init; } = [];
+
+    /// <summary>Gets or sets the probe (connectivity check) options.</summary>
+    public AbLegacyProbeOptions Probe { get; init; } = new();
+
+    /// <summary>Gets or sets the default timeout for read/write operations.</summary>
+    public TimeSpan Timeout { get; init; } = TimeSpan.FromSeconds(2);
+}
+
+public sealed record AbLegacyDeviceOptions(
+    string HostAddress,
+    AbLegacyPlcFamily PlcFamily = AbLegacyPlcFamily.Slc500,
+    string? DeviceName = null);
+
+/// <summary>
+///     One PCCC-backed OPC UA variable. <paramref name="Address"/> is the canonical PCCC
+///     file-address string that parses via <c>AbLegacyAddress.TryParse</c>.
+/// </summary>
+public sealed record AbLegacyTagDefinition(
+    string Name,
+    string DeviceHostAddress,
+    string Address,
+    AbLegacyDataType DataType,
+    bool Writable = true,
+    bool WriteIdempotent = false);
+
+public sealed class AbLegacyProbeOptions
+{
+    /// <summary>Gets or sets a value indicating whether connectivity probing is enabled.</summary>
+    public bool Enabled { get; init; } = true;
+
+    /// <summary>Gets or sets the interval between probe attempts.</summary>
+    public TimeSpan Interval { get; init; } = TimeSpan.FromSeconds(5);
+
+    /// <summary>Gets or sets the timeout for each probe operation.</summary>
+    public TimeSpan Timeout { get; init; } = TimeSpan.FromSeconds(2);
+
+    /// <summary>Gets or sets the probe address (defaults to <c>S:0</c> — status file, first word).</summary>
+    public string? ProbeAddress { get; init; } = "S:0";
+}