CI: remove automated release job (releases are manual)

Author: frstrtr

.github/workflows/build.yml

@@ -239,38 +239,5 @@ jobs:
           name: windows-x86_64
           path: c2pool-*-windows-x86_64.zip*
 
-  # ════════════════════════════════════════════════════════════════════════════
-  # Release — collect artifacts and publish GitHub Release
-  # ════════════════════════════════════════════════════════════════════════════
-  release:
-    name: Publish Release
-    needs: [linux, macos, windows]
-    if: startsWith(github.ref, 'refs/tags/v')
-    runs-on: ubuntu-latest
-    permissions:
-      contents: write
-    steps:
-      - uses: actions/checkout@v6
-
-      - name: Download all artifacts
-        uses: actions/download-artifact@v7
-        with:
-          path: artifacts
-
-      - name: Create SHA256SUMS
-        run: |
-          cd artifacts
-          find . -name '*.tar.gz' -o -name '*.zip' | sort | while read f; do
-            sha256sum "$f" | sed 's|  \./[^/]*/|  |'
-          done > ../SHA256SUMS
-          cat ../SHA256SUMS
-
-      - name: Create GitHub Release
-        uses: softprops/action-gh-release@v2
-        with:
-          draft: true
-          generate_release_notes: true
-          files: |
-            artifacts/**/*.tar.gz
-            artifacts/**/*.zip
-            SHA256SUMS
+  # Releases are built and published manually (not via CI).
+  # See installer/ for packaging scripts (DMG, ZIP, Inno Setup).