Adds a new tooling pattern slug comparing JUnit 5's unannotated API against JUnit 6's adoption of JSpecify @NullMarked, which makes non-null the default and surfaces null contract violations at compile time.

New pattern: tooling/junit6-with-jspecify

// JUnit 5 — no null contracts; must read source to know what's safe
class UserServiceTest {
    @Test void findUser_notFound() {
        assertNull(service.findById("missing")); // null or throws? unclear
    }
}

// JUnit 6 — @NullMarked module; @Nullable where nullable, non-null everywhere else
@NullMarked
class UserServiceTest {
    @Test void findUser_notFound() {
        @Nullable User result = service.findById("missing");
        assertNull(result); // IDE confirms null expectation
    }
}

Changes

• content/tooling/junit6-with-jspecify.json — new pattern (id 111); highlights explicit API contracts, compile-time safety via NullAway/Error Prone/IDEs, and JSpecify as a cross-ecosystem standard shared with Spring and Guava
• content/tooling/aot-class-preloading.json — next updated to tooling/junit6-with-jspecify
• content/language/default-interface-methods.json — prev updated to tooling/junit6-with-jspecify
• Regenerated all site HTML and site/data/snippets.json (111 total patterns)

• Fixes New slug for JUnit 6 with JSpecify versus JUnit 5 #64

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