Add ZIP-wrapped CAMT parsing and real bank file tests

- Support parsing camt.052 ZIP archives in CamtParser and BankingService
- Add CamtZipParserTests for ZIP parsing (single/multi/malformed/empty cases)
- Add CamtRealFileTests: integration tests for real bank exports (ZIP, XML, CAMT, MT940, STA) in git-ignored test data dir
- Update .gitignore and add README.md for test data usage
- Copy test data files in Fuchs.Tests.csproj; add .gitkeep
- Refactor BankingService CAMT mapping logic
- Overhaul connection string config: use {username}/{password} tokens, resolve from secrets at runtime, update appsettings and Key Vault keys

CAMTParser/CamtParser.cs

@@ -1,4 +1,5 @@
-using System.Globalization;
+using System.Globalization;
+using System.IO.Compression;
 using System.Text;
 using System.Xml.Linq;
 
@@ -32,6 +33,14 @@ public sealed class CamtParser
         xml.Contains("camt.05", StringComparison.OrdinalIgnoreCase) ||
         xml.Contains("BkToCstmr", StringComparison.OrdinalIgnoreCase);
 
+    /// <summary>
+    /// Cheap content sniff: is this payload a ZIP archive?  Some banks deliver
+    /// camt.052 intraday reports wrapped in a ZIP containing one or more XML files.
+    /// Checks for the universal PK magic bytes (0x50 0x4B).
+    /// </summary>
+    public static bool LooksLikeZip(ReadOnlySpan<byte> bytes) =>
+        bytes.Length >= 2 && bytes[0] == 0x50 && bytes[1] == 0x4B;
+
     public List<CamtStatement> Parse(Stream stream)
     {
         using var reader = new StreamReader(stream, Encoding.UTF8, detectEncodingFromByteOrderMarks: true, leaveOpen: true);
@@ -40,6 +49,39 @@ public sealed class CamtParser
 
     public List<CamtStatement> Parse(byte[] bytes) => Parse(Encoding.UTF8.GetString(bytes));
 
+    /// <summary>
+    /// Parses all CAMT XML files found inside a ZIP archive and returns
+    /// the combined list of statements.  Non-XML entries and malformed XML
+    /// entries are silently skipped.  Used for camt.052 deliveries where the
+    /// bank wraps one or more intraday reports in a single ZIP file.
+    /// </summary>
+    public List<CamtStatement> ParseZip(byte[] bytes)
+    {
+        using var ms = new MemoryStream(bytes);
+        return ParseZip(ms);
+    }
+
+    /// <inheritdoc cref="ParseZip(byte[])"/>
+    public List<CamtStatement> ParseZip(Stream stream)
+    {
+        var result = new List<CamtStatement>();
+        using var archive = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true);
+        foreach (var entry in archive.Entries)
+        {
+            if (!entry.Name.EndsWith(".xml", StringComparison.OrdinalIgnoreCase))
+                continue;
+            using var entryStream = entry.Open();
+            using var buffer = new MemoryStream();
+            entryStream.CopyTo(buffer);
+            var entryBytes = buffer.ToArray();
+            if (!LooksLikeXml(entryBytes))
+                continue;
+            try { result.AddRange(Parse(entryBytes)); }
+            catch (FormatException) { /* skip malformed XML entries */ }
+        }
+        return result;
+    }
+
     public List<CamtStatement> Parse(string xml)
     {
         var result = new List<CamtStatement>();