fix(ci): release workflow must include webclaw-server

v0.4.0 shipped tarballs without the new webclaw-server binary because
the release workflow predates that binary and was hardcoded for two:

- Package step used `cp ... 2>/dev/null || true`, so a missing binary
  was silently skipped instead of failing the job.
- Docker job's download step copied only webclaw + webclaw-mcp into
  the build context, so Dockerfile.ci's COPY webclaw-server step then
  died with 'file not found'.
- Homebrew formula's install block only covered the same two, so brew
  users would have gotten a release with a missing binary.

Three changes:

1. Package step now explicitly copies all three binaries and drops the
   swallow-all-errors pattern. If a future binary gets renamed or
   removed this step screams instead of silently publishing half a
   release.
2. Docker Download step copies webclaw-server alongside the other
   binaries into the build context.
3. Homebrew formula installs webclaw-server too.

v0.4.0 tag + GitHub Release will be deleted and re-pushed on top of
this commit so the canonical v0.4.0 artifacts are complete. No users
affected — download count was 0 on every broken asset.

.github/workflows/release.yml

@@ -66,8 +66,14 @@ jobs:
           tag="${GITHUB_REF#refs/tags/}"
           staging="webclaw-${tag}-${{ matrix.target }}"
           mkdir "$staging"
-          cp target/${{ matrix.target }}/release/webclaw "$staging/" 2>/dev/null || true
-          cp target/${{ matrix.target }}/release/webclaw-mcp "$staging/" 2>/dev/null || true
+          # Fail loud if any binary is missing. A silent `|| true` on the
+          # copy was how v0.4.0 shipped tarballs that lacked webclaw-server —
+          # don't repeat that mistake. If a future binary gets renamed or
+          # removed, this step should scream, not quietly publish an
+          # incomplete release.
+          cp target/${{ matrix.target }}/release/webclaw "$staging/"
+          cp target/${{ matrix.target }}/release/webclaw-mcp "$staging/"
+          cp target/${{ matrix.target }}/release/webclaw-server "$staging/"
           cp README.md LICENSE "$staging/"
           tar czf "$staging.tar.gz" "$staging"
           echo "ASSET=$staging.tar.gz" >> $GITHUB_ENV
@@ -134,6 +140,7 @@ jobs:
             mkdir -p "binaries-${target}"
             cp "${dir}/webclaw" "binaries-${target}/webclaw"
             cp "${dir}/webclaw-mcp" "binaries-${target}/webclaw-mcp"
+            cp "${dir}/webclaw-server" "binaries-${target}/webclaw-server"
             chmod +x "binaries-${target}"/*
           done
           ls -laR binaries-*/
@@ -220,6 +227,7 @@ jobs:
             def install
               bin.install "webclaw"
               bin.install "webclaw-mcp"
+              bin.install "webclaw-server"
             end
 
             test do