docs: complete XML-doc coverage and strip internal tracking IDs from code comments

Resolve all CommentChecker findings across the gateway server, worker, tests,
and .NET client (314 -> 0 real issues): add missing <returns>/<summary>/<param>
on public and test members, convert Stream/interface overrides to <inheritdoc/>,
and remove internal task/issue tracking IDs (SEC-*, IPC-*, WRK-*, GWC-*, TST-*,
Client.Dotnet-*) from shipped code documentation while preserving the design
rationale prose. Shipped comments should not carry internal bookkeeping, and
complete XML docs keep the analyzer/TreatWarningsAsErrors gate and generated API
docs clean. The 6 remaining flags are heuristic false positives (MD5, UTC-4,
capacity-1, near-1601) left intact so real documentation is not corrupted.

Claude-Session: https://claude.ai/code/session_01DMXXvNuPekkkrTEyPNxEkW

clients/dotnet/ZB.MOM.WW.MxGateway.Client.Cli/CliArguments.cs

@@ -44,6 +44,7 @@ internal sealed class CliArguments
 
     /// <summary>Returns whether the named flag was present in the arguments.</summary>
     /// <param name="name">The flag name (without '--' prefix).</param>
+    /// <returns><c>true</c> if the flag was present; otherwise, <c>false</c>.</returns>
     public bool HasFlag(string name)
     {
         return _flags.Contains(name);
@@ -51,6 +52,7 @@ internal sealed class CliArguments
 
     /// <summary>Returns the value for a named argument, or <c>null</c> if absent.</summary>
     /// <param name="name">The argument name (without '--' prefix).</param>
+    /// <returns>The argument value, or <c>null</c> if the argument is absent.</returns>
     public string? GetOptional(string name)
     {
         return _values.TryGetValue(name, out string? value)
@@ -60,6 +62,7 @@ internal sealed class CliArguments
 
     /// <summary>Returns the value for a required named argument, or throws if absent.</summary>
     /// <param name="name">The argument name (without '--' prefix).</param>
+    /// <returns>The argument value.</returns>
     public string GetRequired(string name)
     {
         string? value = GetOptional(name);
@@ -74,6 +77,7 @@ internal sealed class CliArguments
     /// <summary>Parses and returns an int32 argument, or the default value if absent.</summary>
     /// <param name="name">The argument name (without '--' prefix).</param>
     /// <param name="defaultValue">The default value if the argument is absent; if <c>null</c>, the argument is required.</param>
+    /// <returns>The parsed int32 value.</returns>
     public int GetInt32(string name, int? defaultValue = null)
     {
         string? value = GetOptional(name);
@@ -93,6 +97,7 @@ internal sealed class CliArguments
     /// <summary>Parses and returns a uint32 argument, or the default value if absent.</summary>
     /// <param name="name">The argument name (without '--' prefix).</param>
     /// <param name="defaultValue">The default value if the argument is absent.</param>
+    /// <returns>The parsed uint32 value.</returns>
     public uint GetUInt32(string name, uint defaultValue)
     {
         string? value = GetOptional(name);
@@ -104,6 +109,7 @@ internal sealed class CliArguments
     /// <summary>Parses and returns a uint64 argument, or the default value if absent.</summary>
     /// <param name="name">The argument name (without '--' prefix).</param>
     /// <param name="defaultValue">The default value if the argument is absent.</param>
+    /// <returns>The parsed uint64 value.</returns>
     public ulong GetUInt64(string name, ulong defaultValue)
     {
         string? value = GetOptional(name);
@@ -115,6 +121,7 @@ internal sealed class CliArguments
     /// <summary>Parses and returns a TimeSpan argument, or the default value if absent. Supports "ms", "s", and standard TimeSpan format.</summary>
     /// <param name="name">The argument name (without '--' prefix).</param>
     /// <param name="defaultValue">The default value if the argument is absent.</param>
+    /// <returns>The parsed duration.</returns>
     public TimeSpan GetDuration(string name, TimeSpan defaultValue)
     {
         string? value = GetOptional(name);