chore: localize bot workflows for the JVM family

[rennf93]

The greetings and stale workflows were copied byte-verbatim from guard-core-rs and still referenced Rust tooling (rustc/cargo snippets, MSRV, crate names, conformance commands).

Localized for the JVM family: Kotlin reproduction snippets, Gradle/JDK 17 version output, per-repo module and status pointers, and the JVM conformance command. Action pins and triggers are unchanged.

no-issue

[github-actions]

Thanks for opening your first pull request on guard-core-rs!

Quick checklist before review (most of these are enforced by CI, but worth a glance):

• The PR body says Closes #N for an open issue (the issue-link check enforces it); chores take the no-issue label
• cargo fmt --all -- --check reports no files
• cargo clippy --workspace --all-targets --exclude guard-core-python -- -D warnings is clean
• cargo test --workspace --exclude guard-core-python passes
• The conformance gate is green: cargo test -p guard-core-conformance (a flipped corpus case needs a ledger or xfail update with a written reason)
• RUSTDOCFLAGS="-D warnings" cargo doc --workspace --exclude guard-core-python --no-deps --all-features is clean
• No outer #[allow(...)] in non-test, non-fuzz code; an entry under ## Unreleased in CHANGELOG.md

See AGENTS.md for the boundary rules (the engine crate stays pure, synchronous, CPU-bound) and the conformance honesty policy.

Welcome aboard - a maintainer will review shortly.

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