Fix release publishing and add a CI token fallback

Tag builds since v0.2.2 built all artifacts but never published a release:
- tools/publish_release.sh only assembled AUTH in the GITEA_TOKEN branch; the
  ~/.git-credentials branch set CRED and then used an unbound ${AUTH[@]} under
  `set -u`, so every API call failed and the job ended "could not create or find
  release". It now sets AUTH=(-u "$CRED").
- The repo has no GITEA_TOKEN secret and the runner has no git credentials, so the
  workflow now falls back to the built-in workflow token:
  GITEA_TOKEN: ${{ secrets.GITEA_TOKEN || github.token }}.

v0.2.9 was then built and published locally with all five artifacts (portable
Linux/Windows/macOS, NSIS installer, AppImage) and the release page verified via
the API. v0.2.4-v0.2.8 remain unpublished; they are superseded by the latest.

Docs
- docs/RELEASING.md records the incident and the local-publish fallback.
- TODO gains a release-pipeline follow-up (verify CI on the next tag).
- MEMORY notes the root cause, the missing secret, and which releases exist.
- Version 0.2.10.

docs/RELEASING.md

@@ -37,8 +37,18 @@ The repository ships a Gitea Actions workflow (`.gitea/workflows/build.yml`):
   Linux/Windows/macOS, artifact upload, and — on tags — release publication via
   `tools/publish_release.sh`.
 
-For tag builds, set a repo secret named **`GITEA_TOKEN`** (write:repository scope).
-Without it the workflow still builds and tests, but the release publish step fails.
+For tag builds the workflow uses `GITEA_TOKEN` (write:repository scope) or, when the
+secret is absent, falls back to the workflow's built-in `github.token`. Either is
+enough for the publish step; with neither, the build succeeds but no release is
+created.
+
+> **Incident (2026-10-31):** `tools/publish_release.sh` never set `AUTH` in its
+> `~/.git-credentials` branch, so every API call failed silently (`AUTH[@]` was
+> unbound under `set -u`). Combined with no `GITEA_TOKEN` secret on the repo, tag
+> builds from v0.2.2 to v0.2.8 produced installers but published nothing. The script
+> is fixed (`AUTH=(-u "$CRED")`) and v0.2.9 was published locally with all five
+> artifacts. If CI publishing fails again, run
+> `./tools/publish_release.sh <version>` from a checkout with `~/.git-credentials`.
 
 > **No `actions/cache` for now:** the runner has no local actions-cache service, so
 > `actions/cache` times out against GitHub's cache API. We dropped it (Godot import