Release CI: libmpv/epoxy deps, stable Flutter, multipart asset upload

The v0.1.0 release job failed: media_kit_video needs libmpv-dev and
libepoxy-dev at build time. Build on stable (what's verified locally),
work on root-only runner images, upload the asset as Gitea's multipart
attachment, and reuse an existing release on re-runs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -14,15 +14,17 @@ jobs:
           fetch-depth: 0
 
       - name: Install Linux build deps
+        # media_kit_video links libmpv + epoxy via pkg-config. Runner images
+        # differ: some run as root without sudo.
         run: |
-          if command -v apt-get >/dev/null; then
-            sudo apt-get update
-            sudo apt-get install -y clang cmake ninja-build pkg-config libgtk-3-dev liblzma-dev
-          fi
+          SUDO=sudo; [ "$(id -u)" = 0 ] && SUDO=
+          $SUDO apt-get update
+          $SUDO apt-get install -y clang cmake ninja-build pkg-config libgtk-3-dev \
+            liblzma-dev g++ libmpv-dev libepoxy-dev xz-utils unzip curl python3
 
-      - name: Setup Flutter (beta)
+      - name: Setup Flutter (stable)
         run: |
-          git clone https://github.com/flutter/flutter.git -b beta --depth 1 ~/flutter
+          git clone https://github.com/flutter/flutter.git -b stable --depth 1 ~/flutter
           echo "$HOME/flutter/bin" >> $GITHUB_PATH
 
       - name: Build tarball

tool/release_publish.sh

@@ -35,15 +35,22 @@ else
 fi
 export REL_TAG="$TAG" REL_VER="$VER" REL_NOTES="$NOTES"
 
-echo "creating release $TAG on $REPO ..."
-REL_ID="$(curl -fsS -H "Authorization: token $TOKEN" -H 'Content-Type: application/json' \
+API="$SERVER/api/v1/repos/$REPO"
+# Re-runs reuse the release for this tag instead of failing on a duplicate.
+REL_ID="$(curl -fsS -H "Authorization: token $TOKEN" "$API/releases/tags/$TAG" 2>/dev/null \
+  | python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])' 2>/dev/null || true)"
+if [[ -z "$REL_ID" ]]; then
+  echo "creating release $TAG on $REPO ..."
+  REL_ID="$(curl -fsS -H "Authorization: token $TOKEN" -H 'Content-Type: application/json' \
     -d "$(python3 -c 'import json,os; print(json.dumps({"tag_name": os.environ["REL_TAG"], "name": os.environ["REL_TAG"], "body": "Watch together " + os.environ["REL_VER"] + "\n\n" + os.environ["REL_NOTES"], "draft": False, "prerelease": False}))')" \
-  "$SERVER/api/v1/repos/$REPO/releases" \
+    "$API/releases" \
     | python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])')"
+fi
 echo "release id: $REL_ID"
 
 echo "uploading $ASSET ..."
-curl -fsS -H "Authorization: token $TOKEN" -H 'Content-Type: application/gzip' \
-  --data-binary "@$TARBALL" \
-  "$SERVER/api/v1/repos/$REPO/releases/$REL_ID/assets?name=$ASSET" > /dev/null
+# Gitea's asset API takes a multipart form with an `attachment` field.
+curl -fsS -H "Authorization: token $TOKEN" \
+  -F "attachment=@$TARBALL;type=application/gzip" \
+  "$API/releases/$REL_ID/assets?name=$ASSET" > /dev/null
 echo "published $TAG."