docs: add XML doc comments across src + Sister Projects section in CLAUDE.md

Bulk CommentChecker pass: fills in <param>/<inheritdoc> tags on public
APIs across all 23 src/ projects so the doc-coverage gate is green. Also
adds a Sister Projects section to CLAUDE.md pointing at the MxAccess
Gateway and OtOpcUa sibling repos, and gitignores local credential
captures (*login*.txt) and the wonder-app-vd03 deploy/ artifacts.

src/ScadaLink.CLI/OutputFormatter.cs

@@ -12,16 +12,24 @@ public static class OutputFormatter
         PropertyNamingPolicy = JsonNamingPolicy.CamelCase
     };
 
+    /// <summary>Serializes <paramref name="data"/> to indented JSON and writes it to standard output.</summary>
+    /// <param name="data">The object to serialize; <c>null</c> is serialized as JSON <c>null</c>.</param>
     public static void WriteJson(object? data)
     {
         Console.WriteLine(JsonSerializer.Serialize(data, JsonOptions));
     }
 
+    /// <summary>Writes a JSON error envelope with the given message and code to standard error.</summary>
+    /// <param name="message">Human-readable error description.</param>
+    /// <param name="code">Machine-readable error code.</param>
     public static void WriteError(string message, string code)
     {
         Console.Error.WriteLine(JsonSerializer.Serialize(new { error = message, code }, JsonOptions));
     }
 
+    /// <summary>Writes a plain-text padded table to standard output with the given column headers and data rows.</summary>
+    /// <param name="rows">Data rows; each inner array corresponds to a column in the same order as <paramref name="headers"/>.</param>
+    /// <param name="headers">Column header labels.</param>
     public static void WriteTable(IEnumerable<string[]> rows, string[] headers)
     {
         var allRows = new List<string[]> { headers };