Build agent-mode branch image in CI under a branch tag.

Publish agent-mode pushes as :agent-mode (and :sha-<commit>) so the experimental fork is available from the registry without overwriting the Classic :latest image.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitea/workflows/docker-release.yml

@@ -2,7 +2,7 @@ name: Docker Release
 
 on:
   push:
-    branches: [main]
+    branches: [main, agent-mode]
     tags: ["v*"]
 
 env:
@@ -25,12 +25,19 @@ jobs:
 
           {
             echo "tags<<EOF"
-            echo "${IMAGE}:latest"
             echo "${IMAGE}:sha-${short_sha}"
             if [ "${GITHUB_REF_TYPE}" = "tag" ]; then
               ref_name="${GITHUB_REF_NAME}"
               echo "${IMAGE}:${ref_name}"
               echo "${IMAGE}:${ref_name#v}"
+            elif [ "${GITHUB_REF_NAME}" = "main" ]; then
+              # Only the stable Classic line publishes :latest.
+              echo "${IMAGE}:latest"
+            else
+              # Feature branches (e.g. agent-mode) publish under a branch tag
+              # so they never overwrite the default :latest image.
+              branch_tag="${GITHUB_REF_NAME//\//-}"
+              echo "${IMAGE}:${branch_tag}"
             fi
             echo "EOF"
           } >> "$GITHUB_OUTPUT"