Publish v0.2.11 and document the host disk limit

- Pruned the superseded v0.2.0 and v0.2.9 releases through the API (~565 MB of
  assets) after the host root filesystem hit 100%, which blocked release uploads
  (HTTP 500 "no space left on device") and even git push ("unpacker error").
- Published v0.2.11 locally with the fixed script: all five artifacts verified on
  the release (Linux/Windows/macOS ports, NSIS installer, AppImage).
- TODO records the remaining ~150 MB headroom and the exact host cleanup commands;
  MEMORY and RELEASING describe the disk failure mode and the pruning.

docs/RELEASING.md

@@ -49,6 +49,11 @@ already injects basic-auth credentials for the checkout, and the script reuses t
 header for the API (same server). `github.token` is *not* available in this Gitea
 setup, so do not rely on it.
 
+> **Disk space:** Gitea stores release assets under `/var/lib/gitea/data/attachments` on
+> the host root filesystem (7.8 GB here). When it is full, asset uploads fail with
+> `HTTP 500 … no space left on device` and even `git push` can fail with "unpacker error".
+> `publish_release.sh` now verifies the asset count and exits non-zero, so this is visible.
+>
 > **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