Support mise version manager for Java and Node via idiomatic version files

Description

Developers using mise don't get the repo's required Java/Node versions automatically — only SDKMAN (.sdkmanrc) and nvm (.nvmrc) are wired up. mise can parse both files natively as "idiomatic version files", but that support is opt-in per tool in current mise versions.

Enable it in the repo's existing .mise.toml so mise resolves Java from .sdkmanrc (25.0.2-ms → microsoft-25.0.2) and Node from .nvmrc (v22.15.0). No versions are duplicated: .sdkmanrc stays the single source of truth (CI's setup-java action parses it), and SDKMAN/nvm users and CI are unaffected.

Acceptance Criteria

• idiomatic_version_file_enable_tools = ["java", "node"] added under [settings] in .mise.toml
• mise ls --current in the repo resolves java microsoft-25.0.2 (from .sdkmanrc) and node 22.15.0 (from .nvmrc)
• No version numbers duplicated in .mise.toml; CI and non-mise workflows unchanged

Additional Context

Work is already implemented and verified locally; PR to follow.