ci: default published install checks to latest

[mertushka]

Purpose

Prevent manual Published Install runs from silently testing the obsolete 0.1.0-alpha.0 package currently referenced by the npm next tag.

Changes

• default the manual package spec to @mertushka/webrtc-node@latest
• clarify that maintainers can pass a tag or exact version
• document explicit prerelease/version validation in docs/development.md

Impact

• Public/runtime behavior: none
• Native addon: none
• WPT/conformance: none
• Browser interoperability: none
• Release publishing: unchanged; manual prerelease publication can still use the next tag
• npm registry metadata: unchanged

Validation

• npm run check
• git diff --check
• actionlint 1.7.12 across all workflows, using the checksum-verified upstream Windows release binary
• verified npm currently resolves latest to 0.1.6 and next to 0.1.0-alpha.0