ci: drop Upload wheel artifacts step (redundant with release)

artifact-upload served two purposes:
 1. download wheel from Actions UI for debugging
 2. (future) hand off to cross-job tests

Neither is currently used: distribution already goes through the
Gitea release via create-release.sh, and there are no downstream
jobs that need the artifact.

Removes the actions/upload-artifact@v4 step + the if: success()
gate. The build is now: uv build -> release (tag only) -> bark
notify. Cleaner, one fewer thing to fail on.

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

.github/workflows/build.yml

@@ -31,14 +31,6 @@ jobs:
           UV_DEFAULT_INDEX: "https://pypi.tuna.tsinghua.edu.cn/simple/"
         run: uv build
 
-      - name: Upload wheel artifacts
-        if: success()
-        uses: actions/upload-artifact@v4
-        with:
-          name: snapshot-dist
-          path: dist/snapshot-*
-          if-no-files-found: error
-
       # Only create a release + attach dist/ assets when pushing a v* tag.
       # On branch pushes / pull requests this step is skipped entirely.
       # The release logic is in a separate script to avoid embedding a JSON