docs: spell out what a missing RELEASE_TOKEN actually does

The note said Codeberg needs the secret but not what happens without it,
so the failure mode had to be inferred from a red job. Record it: build
and packaging still succeed, the upload step fails on authentication and
takes the job with it, and the release is published with no assets.

Not "the upload step is skipped", which is what the comment in
.forgejo/workflows/release.yml claims. That step is guarded only by
`if: github.event_name == 'release'` — there is no token check and no
continue-on-error, so an absent or unscoped token makes it fail rather
than skip. Skipping is the workflow_dispatch path. The workflow comment
is still wrong and is left for a separate change.

Also name why GitHub needs no setup: softprops/action-gh-release falls
back to the built-in GITHUB_TOKEN and the workflow grants contents:write.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/DEVELOPMENT.md

@@ -292,4 +292,8 @@ also allows a manual, upload-free build to smoke-test the pipeline.
 
 Codeberg publishing needs a repository secret named `RELEASE_TOKEN` (a Codeberg
 access token with the `write:repository` scope) under
-**Settings → Actions → Secrets**. GitHub uses the built-in `GITHUB_TOKEN`.
+**Settings → Actions → Secrets**. Without it the build and packaging steps still
+succeed, but the upload step fails on authentication and takes the job down with
+it, leaving a published release with no attached assets. GitHub needs no such
+setup: `softprops/action-gh-release` falls back to the built-in `GITHUB_TOKEN`,
+and the workflow already grants it `contents: write`.