Add .gitignore and remove sensitive export files from tracking

.gitignore

@@ -1,4 +1,16 @@
-Thumbs.db
+# Sensitive exports
+code_export.txt
+code_export.ps1.test.txt
+*.test.txt
+
+# OS files
 .DS_Store
-gitea-token*.txt
+Thumbs.db
-gitea-token*.txt.sig
+
+# IDE
+.vscode/
+.idea/
+
+# Temporary files
+*.tmp
+*.log