chore(release): 1.8.20

[florianmousseau]

Stamps [Unreleased] as 1.8.20 and bumps package.json. No code changes.

Patch, per RELEASING.md: nothing here breaks an app, and neither an added
option nor a new entry point moves the second digit.

What it publishes

Four merges have been sitting on main since 1.8.19:

• One register function per widget (feat(widgets): one register function per widget #100), so an app stops shipping the
  widgets it never renders. defineStatus alone is 5.1 kB brotli over 5
  modules against 101.5 kB for the full barrel.
• Four accessibility defects an audit measured (fix(widgets): four accessibility defects an audit measured #101): two severity colors
  below 4.5:1 while used as text, a blocking gate that did not hold the Tab
  key, nothing ever announced to a screen reader, and a spinner that ignored
  prefers-reduced-motion.
• exportBackup({ plaintext: true }) (feat(store): a readable copy of a protected store, on request #102), a readable copy of a
  protected store without rewriting the destination.
• A release dispatch typed with a leading v no longer fails (fix(ci): absorb the v prefix a release dispatch is typed with #103).

The two ### Added blocks arrived from separate PRs and are merged into one
section here; the prose is unchanged, and I checked line by line that nothing
was dropped in the move.

After the merge

release.yml with 1.8.20 to tag and cut the GitHub Release, then
publish.yml with v1.8.20 - the release event raised by GITHUB_TOKEN
cannot start the publish workflow on its own, as its header explains.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud