Update contributing docs to mention semver

[danielcardoso5]

Our releases should follow semver, but it was not clearly stated in the docs.

Disables release of major versions to prevent accidental bumps. Matches v0 package scripts.

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Note

Low Risk
Documentation and release-script validation only; no runtime library behavior changes.

Overview
Documents Semantic Versioning in the stable-release section of CONTRIBUTING.md, including when to use patch vs minor bumps and that major bumps are intentionally disabled to keep v1 backward compatible.

Adds a bump-type → pnpm run release command table and tightens the release steps (including a stable-version example instead of beta-style version strings).

Aligns scripts/release.js with the docs by removing major from allowed official bump types, with a comment explaining it avoids accidental major releases.

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[danielcardoso5]

Updated as I plan to release 2.0.0 due to the breaking changes introduced in #265