chore(release): prepare v0.1.3

[muxx]

Summary

• bump all AgentBox SDK packages to 0.1.3
• update Python lock files and versioned pkg.go.dev links
• regenerate the public reference contract and checksums

Verification

• node scripts/check-release-versions.mjs v0.1.3
• make generate (second run produced no diff)
• make go-check
• pnpm format:check
• pnpm lint
• pnpm typecheck
• pnpm test
• ./scripts/build-release.sh
• node scripts/check-public-artifacts.mjs release
• ./scripts/test-release-artifacts.sh
• ./scripts/test-release-runtime.sh (local KVM backend; all JavaScript, Python sync/async, CLI, Go core and Code Interpreter scenarios passed)