[AI] Fix /update-vrt merge step when only one shard has changes (#7802)

The Merge VRT Patches job collects shard patches with the glob
`/tmp/shard-patches/*/vrt-shard.patch`, which assumes every downloaded
artifact lands in its own `path/<artifact-name>/` subdirectory. But
actions/download-artifact only does that when 2+ artifacts match the
pattern; when exactly one matches it unpacks the artifact directly into
`path`. So whenever a `/update-vrt` run touches snapshots in a single
shard (the common case) the patch ends up at
`/tmp/shard-patches/vrt-shard.patch`, the glob matches nothing, and the
job reports "No shard patches to merge" despite a patch having been
generated (e.g. run 25679233565).

Replace the glob with a recursive `find` so the patches are located
under either layout. `merge-multiple: true` is not an option here
because every shard artifact contains a file literally named
`vrt-shard.patch` and they would overwrite each other.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/vrt-update-generate.yml

@@ -264,8 +264,11 @@ jobs:
           git config --global user.name "github-actions[bot]"
           git config --global user.email "github-actions[bot]@users.noreply.github.com"
 
-          shopt -s nullglob
-          patches=(/tmp/shard-patches/*/vrt-shard.patch)
+          # actions/download-artifact puts a lone matched artifact directly in
+          # `path` but gives each of several its own `path/<name>/` subdir, so
+          # recurse instead of globbing `*/vrt-shard.patch` (which would miss
+          # the common single-shard case).
+          mapfile -t patches < <(find /tmp/shard-patches -type f -name 'vrt-shard.patch' | sort)
 
           if [ ${#patches[@]} -eq 0 ]; then
             echo "has_changes=false" >> "$GITHUB_OUTPUT"

upcoming-release-notes/7802.md

@@ -0,0 +1,6 @@
+---
+category: Maintenance
+authors: [MatissJanis]
+---
+
+Fix `/update-vrt` screenshot merge operation when exactly one patch is generated