Add Maven dependencies for improved code quality

Add essential Maven dependencies that enhance code quality and safety through a consultative, question-driven approach. This is an interactive SKILL.

Prerequisites: Run ./mvnw validate or mvn validate before any changes. If validation fails, stop and ask the user to fix issues—do not proceed until resolved.

Components: JSpecify (nullness annotations, provided scope), Error Prone + NullAway (enhanced static analysis with compile-time null checking), VAVR (functional programming with Try/Either and immutable collections), and ArchUnit (architecture rule enforcement, test scope).

Before asking questions: Read the reference to use the exact wording and options from the template. Ask questions one-by-one in strict order (JSpecify → Enhanced Compiler Analysis (conditional) → VAVR → ArchUnit) and add only what the user selects. Use consultative language, present trade-offs, and wait for user responses before implementing.

Reference

For detailed guidance, examples, and constraints, see references/111-java-maven-dependencies.md.