[KM-493] [DED][AI] Fix source extraction in chat

changes:
- Add .vscode/launch.json with debugpy config for FastAPI via uvicorn on port 7860
- Fix _extract_sources in chat.py to read metadata from nested `data` key
- Add debug log for extracted sources

tikcet: https://bukittechnology.atlassian.net/browse/KM-493

.vscode/launch.json

@@ -0,0 +1,25 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "DataEyond: FastAPI (debug)",
+            "type": "debugpy",
+            "request": "launch",
+            "module": "uvicorn",
+            "args": [
+                "main:app",
+                "--host", "0.0.0.0",
+                "--port", "7860",
+                "--reload"
+            ],
+            "jinja": true,
+            "justMyCode": true,
+            "envFile": "${workspaceFolder}/.env",
+            "console": "integratedTerminal",
+            "cwd": "${workspaceFolder}"
+        }
+    ]
+}

src/api/v1/chat.py

@@ -66,10 +66,11 @@ def _extract_sources(results: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
         if key not in seen:
             seen.add(key)
             sources.append({
-                "document_id": meta.get("document_id"),
-                "filename": meta.get("filename", "Unknown"),
-                "page_label": meta.get("page_label"),
+                "document_id": meta.get("data", {}).get("document_id"),
+                "filename": meta.get("data", {}).get("filename", "Unknown"),
+                "page_label": meta.get("data", {}).get("page_label", "Unknown"),
             })
+    logger.debug(f"Extracted sources: {sources}")
     return sources