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.

opencode.jsonc

@@ -0,0 +1,10 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "skills": {
+    "paths": [
+      "~/.config/opencode/skills/external/andrej-karpathy-skills/skills",
+      "~/.config/opencode/skills/external/ponytail/skills",
+      "~/.config/opencode/skills/external/i-have-adhd/skills"
+    ]
+  }
+}