Refactor code structure and optimize performance across multiple modules

.gitignore

@@ -1,25 +1,50 @@
-HELP.md
+### Build output ###
 target/
-.mvn/wrapper/maven-wrapper.jar
+build/
 !**/src/main/**/target/
 !**/src/test/**/target/
+!**/src/main/**/build/
+!**/src/test/**/build/
 
-### OS / local workspace ###
-.DS_Store
-.codex
-.claude/
-.cursor/
+### Maven ###
+.mvn/wrapper/maven-wrapper.jar
 .m2/
+HELP.md
 
-### Logs / env ###
-*.log
+### Secrets & credentials ###
+# Never commit real credentials. See docs/configuration.md and .env.example.
 .env
 .env.*
+!.env.example
+*.pem
+*.p12
+*.key
+google-key.json
+**/keys/google-key.json
+src/main/resources/application-local.properties
 
-### Local secrets ###
-/google-key.json
+### Logs ###
+*.log
+logs/
 
-### STS ###
+### OS ###
+.DS_Store
+Thumbs.db
+
+### AI / editor tooling ###
+.claude/
+.cursor/
+.codex
+.qwen/
+.aider*
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### Eclipse / STS ###
 .apt_generated
 .classpath
 .factorypath
@@ -28,21 +53,12 @@ target/
 .springBeans
 .sts4-cache
 
-### IntelliJ IDEA ###
-.idea
-*.iws
-*.iml
-*.ipr
-
 ### NetBeans ###
 /nbproject/private/
 /nbbuild/
 /dist/
 /nbdist/
 /.nb-gradle/
-build/
-!**/src/main/**/build/
-!**/src/test/**/build/
 
 ### VS Code ###
 .vscode/