fix(ablegacy): final review I3 — default reverts to libplctag; Native is opt-in

On a wire the native PCCC path is proven only for N-file reads/writes and
one F8 read (ab_server). An absent transport key now resolves to Libplctag
for every family; explicit Native still wins and still warns once per
instance on PLC-5/LogixPccc. AdminUI dropdown, CLI help, evidence claims
(PcccFileType, AbLegacy.md wire-evidence table, release note) corrected:
S:0 (default probe) and B/T/C/R/S/L/ST/A/O/I are unverified natively.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

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

@@ -27,9 +27,9 @@ public sealed class AbLegacyDriverOptions
 
     /// <summary>
     ///     Which transport stack the driver, its Test Connect probe and the CLI use. <c>null</c> (the
-    ///     <c>transport</c> key absent) means "use the default": <see cref="AbLegacyTransport.Native"/>, UNLESS
-    ///     any configured device is a PLC-5 or LogixPccc (limited native support), in which case the whole
-    ///     driver resolves to <see cref="AbLegacyTransport.Libplctag"/>. An explicit value always wins. The
+    ///     <c>transport</c> key absent) means "use the default": <see cref="AbLegacyTransport.Libplctag"/> for
+    ///     every family. <see cref="AbLegacyTransport.Native"/> is opt-in (final review I3: on a wire it is proven
+    ///     only for N-file reads/writes and one F8 read). An explicit value always wins. The
     ///     effective transport is resolved in one place, <c>AbLegacyTransportResolver</c>.
     ///     <para>Changing this takes effect when the driver instance is RECREATED, not on
     ///     <c>ReinitializeAsync</c>: the tag factory is chosen once in the constructor and held across