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.Commons/Entities/InboundApi/ApiKey.cs

@@ -10,7 +10,9 @@ namespace ScadaLink.Commons.Entities.InboundApi;
 /// </summary>
 public class ApiKey
 {
+    /// <summary>Database primary key.</summary>
     public int Id { get; set; }
+    /// <summary>Display name for the API key.</summary>
     public string Name { get; set; }
 
     /// <summary>
@@ -20,6 +22,7 @@ public class ApiKey
     /// </summary>
     public string KeyHash { get; set; }
 
+    /// <summary>When false, the key is rejected even if the hash matches.</summary>
     public bool IsEnabled { get; set; }
 
     /// <summary>
@@ -28,6 +31,8 @@ public class ApiKey
     /// never holds the plaintext. Production code paths that have a configured pepper
     /// should use <see cref="FromHash(string, string)"/> with a peppered hash instead.
     /// </summary>
+    /// <param name="name">Display name for the API key.</param>
+    /// <param name="keyValue">Plaintext key value; hashed immediately and never stored.</param>
     public ApiKey(string name, string keyValue)
     {
         Name = name ?? throw new ArgumentNullException(nameof(name));
@@ -50,6 +55,8 @@ public class ApiKey
     /// path, which generates a random key, hashes it with the configured (peppered)
     /// <see cref="IApiKeyHasher"/>, and stores only the resulting hash.
     /// </summary>
+    /// <param name="name">Display name for the API key.</param>
+    /// <param name="keyHash">Pre-computed keyed hash of the API key value.</param>
     public static ApiKey FromHash(string name, string keyHash)
     {
         return new ApiKey