Fix release workflow to upload platform-specific binary names

Previously all binaries were uploaded with the same name 'piglet',
causing them to overwrite each other. Now each binary is renamed
to include the target platform (e.g., piglet-x86_64-unknown-linux-gnu)
before uploading.

This ensures all 4 platform binaries are available in the release.

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

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

.github/workflows/release.yml

@@ -151,11 +151,14 @@ jobs:
         if: matrix.os == 'macos-latest'
         run: strip target/${{ matrix.target }}/release/piglet
 
+      - name: Rename binary
+        run: |
+          cp target/${{ matrix.target }}/release/piglet piglet-${{ matrix.target }}
+
       - name: Upload release binary
         uses: softprops/action-gh-release@v1
         with:
-          files: target/${{ matrix.target }}/release/piglet
+          files: piglet-${{ matrix.target }}
-          name: piglet-${{ matrix.target }}
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}