Refactor PDF handling and update config

Simplified the return logic in `SwissQrCodeController` by removing conditional checks and directly returning the result.

Refactored `DevExpressPdfProcessor` to handle encrypted PDFs more effectively by checking for encryption before attempting to load with DevExpress, thus avoiding potential errors. Metadata extraction is now limited to non-encrypted PDFs.

Added `opencode.jsonc` configuration file to define schema and specify paths for integrating external AI skills with the OpenCode AI platform.

DocumentService.Infrastructure/Services/PdfProcessing/DevExpressPdfProcessor.cs

@@ -123,23 +123,7 @@ public class DevExpressPdfProcessor : IPdfProcessor
             pdfBytes = memoryStream.ToArray();
         }
 
-        // 3. Load PDF with DevExpress Document API
-        // Reset position for DevExpress (seekable streams only)
-        if (pdfStream.CanSeek)
-        {
-            pdfStream.Position = 0;
-        }
-        
-        using var processor = new PdfDocumentProcessor();
-        processor.LoadDocument(pdfStream);
-
-        var document = processor.Document;
-
-        // 4. Extract basic metadata
-        int pageCount = document.Pages.Count;
-        string pdfVersion = document.Version.ToString();
-        
-        // 5. Check encryption (scan PDF raw data for /Encrypt keyword)
+        // 3. Check encryption (scan PDF raw data for /Encrypt keyword)
         bool encrypted = DetectEncryption(pdfBytes);
 
         // 6. Check PDF/A conformance (scan PDF raw data for PDF/A identifier)
@@ -149,13 +133,42 @@ public class DevExpressPdfProcessor : IPdfProcessor
         var errors = new List<string>();
         var warnings = new List<string>();
 
-        // If encrypted, PDF/A compliance is not possible
-        if (encrypted && isPdfACompliant)
+        int pageCount = 0;
+        string pdfVersion = string.Empty;
+
+        // If encrypted, skip DevExpress loading (it will throw) and return early
+        if (encrypted)
         {
-            errors.Add("PDF/A documents cannot be encrypted");
             isPdfACompliant = false;
+            errors.Add("PDF/A documents cannot be encrypted");
+
+            return new PdfAValidationResult
+            {
+                IsValid = false,
+                PdfVersion = pdfVersion,
+                PageCount = pageCount,
+                FileSize = pdfBytes.Length,
+                Encrypted = true,
+                PdfAVersion = null,
+                PdfACompliant = false,
+                Errors = errors,
+                Warnings = warnings
+            };
         }
 
+        // Load PDF with DevExpress Document API (only for non-encrypted PDFs)
+        if (pdfStream.CanSeek)
+            pdfStream.Position = 0;
+
+        using var processor = new PdfDocumentProcessor();
+        processor.LoadDocument(pdfStream);
+
+        var document = processor.Document;
+
+        // 4. Extract basic metadata
+        pageCount = document.Pages.Count;
+        pdfVersion = document.Version.ToString();
+
         // Basic PDF/A validation checks
         if (isPdfACompliant)
         {