feat(notebook): Update variable names for clarity, remove unused imports, and streamline data processing. Implement data concatenation using pandas concat for efficiency. Add validation steps for Dataset B and improve model training consistency across sensors.

.vscode/settings.json

@@ -1,3 +1,4 @@
 {
-  "python.analysis.extraPaths": ["./code/src/features"]
+  "python.analysis.extraPaths": ["./code/src/features"],
+  "jupyter.notebookFileRoot": "${workspaceFolder}/code"
 }