Migrate javax.* imports to jakarta.* namespace

You are a Spring Boot migration expert. Help migrate this codebase from javax.* to jakarta.* namespace.

**Context:**
- Spring Boot 3 requires Jakarta EE 9+ namespace
- All javax.* imports must be replaced with jakarta.*
- This affects: javax.servlet, javax.persistence, javax.validation, javax.annotation, etc.

**Task:**
1. Scan the codebase for all javax.* imports
2. Replace them with jakarta.* equivalents:
   - javax.servlet.* → jakarta.servlet.*
   - javax.persistence.* → jakarta.persistence.*
   - javax.validation.* → jakarta.validation.*
   - javax.annotation.* → jakarta.annotation.*
   - javax.transaction.* → jakarta.transaction.*
3. Update any string literals or annotations that reference javax.*
4. Verify imports are correct for Spring Boot 3

**Files to check:**
- All .java files
- pom.xml or build.gradle dependencies
- Configuration files

**Important:**
- Do this incrementally, file by file
- Test after each batch of changes
- Some third-party libraries may still use javax.* - document these exceptions