Fix .gitignore to exclude user-specific files

- Remove tracked .idea/dataSources.xml (user-specific DB config)
- Remove tracked .idea/vcs.xml (user-specific VCS settings)
- Use whitelist approach for .idea/ directory
- Add patterns for temp/backup files (*.backup*, *.py, temp_*.json, etc.)

.gitignore

@@ -15,6 +15,11 @@ target/
 ### IntelliJ IDEA ###
 .idea/*
 !.idea/runConfigurations/
+!.idea/.gitignore
+!.idea/compiler.xml
+!.idea/encodings.xml
+!.idea/jarRepositories.xml
+!.idea/misc.xml
 *.iws
 *.iml
 *.ipr
@@ -38,3 +43,13 @@ build/
 ### Project Specific ###
 tmp/
 uploads/
+
+### Temp and backup files ###
+*.backup
+*.backup*
+*.bak
+*.tmp
+*.py
+temp_*.json
+last_part.json
+fix_*.py