Initial import of the CBDDC codebase with docs and tests. Add a .NET-focused gitignore to keep generated artifacts out of source control.

src/ZB.MOM.WW.CBDDC.Core/Cache/IDocumentCache.cs

@@ -0,0 +1,45 @@
+using System.Threading.Tasks;
+
+namespace ZB.MOM.WW.CBDDC.Core.Cache
+{
+    /// <summary>
+    /// Defines operations for caching documents by collection and key.
+    /// </summary>
+    public interface IDocumentCache
+    {
+        /// <summary>
+        /// Clears all cached documents.
+        /// </summary>
+        void Clear();
+
+        /// <summary>
+        /// Gets a cached document by collection and key.
+        /// </summary>
+        /// <param name="collection">The collection name.</param>
+        /// <param name="key">The document key.</param>
+        /// <returns>The cached document, or <see langword="null"/> if not found.</returns>
+        Task<Document?> Get(string collection, string key);
+
+        /// <summary>
+        /// Gets cache hit/miss statistics.
+        /// </summary>
+        /// <returns>A tuple containing hits, misses, current size, and hit rate.</returns>
+        (long Hits, long Misses, int Size, double HitRate) GetStatistics();
+
+        /// <summary>
+        /// Removes a cached document by collection and key.
+        /// </summary>
+        /// <param name="collection">The collection name.</param>
+        /// <param name="key">The document key.</param>
+        void Remove(string collection, string key);
+
+        /// <summary>
+        /// Adds or updates a cached document.
+        /// </summary>
+        /// <param name="collection">The collection name.</param>
+        /// <param name="key">The document key.</param>
+        /// <param name="document">The document to cache.</param>
+        /// <returns>A task that represents the asynchronous operation.</returns>
+        Task Set(string collection, string key, Document document);
+    }
+}