ADR: pinned prerelease versioning for beta release lines

[pomfrida]

Write an ADR documenting the versioning decision implemented in #5180 (eds-tokens) and #5190 (eds-core-react-next): release-please versioning: prerelease + prerelease: true pins both beta lines at a fixed 3.0.0-beta.N series where every commit type only bumps the counter. Should capture the rejected alternatives (custom version automation in the publish workflow per #5141's original prescription, a separate beta component), the version.txt/package.json split for workspace:^ dependents, and the inverted "no ! in beta commits" rule.

Related: #5141, #5120

[claude]

These issues look related and may provide useful context for the ADR:

• fix: pin EDS 2.0 beta releases to a fixed 3.0.0-beta.N series #5141 — fix: pin EDS 2.0 beta releases to a fixed 3.0.0-beta.N series (closed): the original decision and release-please prescription this ADR is meant to document, including the rejected custom-version-automation approach.
• 📦 eds-tokens packaging & release (beta flags → 3.0.0) #5120 — 📦 eds-tokens packaging & release (beta flags → 3.0.0) (closed): defines the beta-flag-then-major release strategy for eds-tokens that the pinned versioning implements.
• Publish the new tokens as a beta release line for @equinor/eds-tokens #5172 — Publish the new tokens as a beta release line for @equinor/eds-tokens (closed): establishes the eds-tokens beta release line that this versioning scheme pins.
• chore: run npm deprecate on eds-tokens 2.x at 3.0.0 graduation #5193 — chore: run npm deprecate on eds-tokens 2.x at 3.0.0 graduation (open): covers the beta → 3.0.0 graduation step, the far end of the same versioning lifecycle.

This comment was generated by an LLM and may be inaccurate. Please verify that the linked issues are actually relevant.