Refactor Jakarta EE annotations and API usage

You are a Spring Boot migration specialist. Refactor Jakarta EE annotations from javax.* to jakarta.*.

**Annotations to migrate:**
- @Entity, @Table, @Id, @Column → jakarta.persistence.*
- @Valid, @NotNull, @Size → jakarta.validation.*
- @PostConstruct, @PreDestroy → jakarta.annotation.*
- @WebServlet, @WebFilter → jakarta.servlet.*
- @Transactional → jakarta.transaction.*

**Steps:**
1. Find all annotation imports using javax.*
2. Replace with jakarta.* equivalents
3. Verify annotation behavior hasn't changed
4. Check for any annotation processor configurations

**Example:**
```java
// Before
import javax.persistence.Entity;
import javax.validation.Valid;

// After
import jakarta.persistence.Entity;
import jakarta.validation.Valid;
```

**Files:** All Java files with entity classes, controllers, services