Release 0.3.1: network interception helpers, fix release-token secret name

- Bump package.json/lock to 0.3.1, move Unreleased CHANGELOG entries under it
- Fix release CI job: secrets.GITEA_TOKEN can never be set (Gitea rejects
  that literal secret name), so the release job has been unable to create
  a Gitea release since it was added. Renamed to RELEASE_TOKEN throughout
  and set the secret on this repo.
- Bump install-pin examples (README, docs/CONSUMER.md) to #v0.3.1

ROADMAP.md

@@ -2,7 +2,7 @@
 
 Living plan for making `@levkin/playkit` more useful across Levkin repos.
 
-## Now (v0.3) — shipped
+## Now (v0.3.1) — shipped
 
 - [x] Browser helpers with retries (`click`, `fill`, `safeGoto`, visibility waits)
 - [x] `BasePage` for Page Objects