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/Interfaces/Transport/IBundleSessionStore.cs

@@ -4,8 +4,15 @@ namespace ScadaLink.Commons.Interfaces.Transport;
 
 public interface IBundleSessionStore
 {
+    /// <summary>Stores the session and returns it; overwrites any existing session with the same id.</summary>
+    /// <param name="session">The session to store.</param>
     BundleSession Open(BundleSession session);
+    /// <summary>Returns the session for the given id, or null if not found or expired.</summary>
+    /// <param name="sessionId">The session identifier to look up.</param>
     BundleSession? Get(Guid sessionId);
+    /// <summary>Removes the session for the given id, if present.</summary>
+    /// <param name="sessionId">The session identifier to remove.</param>
     void Remove(Guid sessionId);
+    /// <summary>Removes all sessions whose expiry has passed.</summary>
     void EvictExpired();
 }