Migrate to Java 25

[Copilot]

Migrate project from Java 11 to Java 25 using OpenRewrite's UpgradeToJava25 recipe.

Build & CI

• Compiler target/release 11 → 25, maven-compiler-plugin 3.11.0 → 3.15.0
• Surefire/Failsafe 3.2.2 → 3.5.5 with --add-opens args for module encapsulation
• CI workflow JDK 11 → 25

Code modernization

• Pattern matching instanceof — eliminates redundant casts
• Switch expressions — arrow syntax replacing verbose switch/case/break
• Unnamed variables — catch (IllegalArgumentException _) where exception is unused
• String.formatted() — replaces String.format()
• Flexible main — void main(String[]) instead of public static void main(String[])

// Before
if (event instanceof Wizard) {
    Wizard w = (Wizard) event;
    return "Wizard registration: " + w.getFirstName();
}

// After
if (event instanceof Wizard w) {
    return "Wizard registration: " + w.getFirstName();
}

This change was produced with Moderne CLI and Moderne Agent Tools (MCP).