Add .gitignore to exclude temporary files and reports

.gitignore

@@ -0,0 +1,34 @@
+# Battery Life Optimizer .gitignore
+
+# Generated reports
+*.html
+*.csv
+reports/
+.battery-optimizer/
+
+# Temporary files
+*.tmp
+*.bak
+*.swp
+*~
+
+# Log files
+*.log
+
+# OS generated files
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+
+# IDE files
+.vscode/
+.idea/
+*.sublime-*
+
+# System backup files
+*.backup.*
+/etc/tlp.conf.backup.*