fix: use correct vendored-openssl feature for Linux builds

Linux builds were failing because we made openssl optional but
were using the wrong feature flag. Use the vendored-openssl
feature we defined which enables openssl?/vendored.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: runonthespot

.github/workflows/release.yml

@@ -135,7 +135,7 @@ jobs:
             ${{ env.CARGO_CMD }} build --locked --release --target ${{ matrix.target }} --package ck-search
           else
             # Use vendored OpenSSL on Unix platforms
-            ${{ env.CARGO_CMD }} build --locked --release --target ${{ matrix.target }} --package ck-search --features=openssl/vendored
+            ${{ env.CARGO_CMD }} build --locked --release --target ${{ matrix.target }} --package ck-search --features=vendored-openssl
           fi
         shell: bash