chore: Migrate Java version from 8 to 11

[devin-ai-integration]

chore: Migrate Java version from 8 to 11

Summary

Updates the banking application's Java version configuration from Java 8 to Java 11 as part of the larger migration plan. This PR includes:

• Maven configuration: Updated pom.xml to set java.version property from 1.8 to 11
• Documentation updates: Updated both README files to specify Java 11 as the minimum requirement
• IDE setup documentation: Added comprehensive setup instructions for Eclipse/STS, IntelliJ IDEA, and VS Code to help developers configure their environments for Java 11

The application continues to use Spring Boot 2.1.4.RELEASE with existing dependencies.

Review & Testing Checklist for Human

⚠️ High Priority - The following items require careful verification as local testing was blocked by environment constraints:

• Verify compilation: Run mvn clean compile to ensure the project compiles successfully with Java 11
• Verify Spring Boot compatibility: Confirm Spring Boot 2.1.4.RELEASE works correctly with Java 11 (released April 2019, Java 11 support should be present)
• Test application startup: Run mvn spring-boot:run and verify the application starts without errors on port 8989
• Test core functionality: Access Swagger UI at http://localhost:8989/bank-api/swagger-ui.html and verify REST endpoints work
• Verify H2 console: Access H2 database console at http://localhost:8989/bank-api/h2-console/ and ensure database connectivity works

Test Plan Recommendation

1. Run full Maven lifecycle: mvn clean compile test package
2. Start the application and perform basic banking operations via Swagger UI
3. Create a customer, add an account, perform a transfer transaction
4. Verify transaction history and account balances are correct

Notes

• Environment Issue: Local testing failed with "invalid target release: 11" due to Java 8 environment configuration
• Dependencies: All Maven dependencies (Lombok, Swagger, H2, Spring Security) should be compatible with Java 11, but runtime verification is needed
• IDE Documentation: Added detailed setup instructions for three major IDEs to help team transition smoothly

Link to Devin run: https://app.devin.ai/sessions/838286fcbee74e08ba74adb2513ba908
Requested by: Jaime Mizrachi (@jaime-leo)

[devin-ai-integration]

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