fix: statically link zlib on Windows to eliminate zlib1.dll dependency

Windows users reported needing zlib1.dll bundled with surge.exe.
CI tests passed because MSYS2 provides the DLL at runtime, but end
users without MSYS2 don't have it. Adding -static to CCOPT on Windows
produces a self-contained binary with no external DLL dependencies.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: steinbeck

.github/workflows/build.yml

@@ -191,7 +191,7 @@ jobs:
           make surge \
             NAUTY=$(cygpath -u "$GITHUB_WORKSPACE")/nauty2_9_3 \
             NAUTYLIB=$(cygpath -u "$GITHUB_WORKSPACE")/nauty2_9_3 \
-            CCOPT="-O3"
+            CCOPT="-O3 -static"
 
       - name: Test surge
         working-directory: src

.github/workflows/release.yml

@@ -13,12 +13,15 @@ jobs:
           - os: ubuntu-latest
             artifact: surge-linux-x86_64
             binary: surge
+            ccopt: "-O3"
           - os: macos-14
             artifact: surge-macos-arm64
             binary: surge
+            ccopt: "-O3"
           - os: windows-latest
             artifact: surge-windows-x86_64
             binary: surge.exe
+            ccopt: "-O3 -static"
     runs-on: ${{ matrix.os }}
     defaults:
       run:
@@ -66,7 +69,7 @@ jobs:
           make surge \
             NAUTY=$(cygpath -u "$GITHUB_WORKSPACE" 2>/dev/null || echo "$GITHUB_WORKSPACE")/nauty2_9_3 \
             NAUTYLIB=$(cygpath -u "$GITHUB_WORKSPACE" 2>/dev/null || echo "$GITHUB_WORKSPACE")/nauty2_9_3 \
-            CCOPT="-O3"
+            CCOPT="${{ matrix.ccopt }}"
 
       - name: Build surge (macOS)
         if: startsWith(matrix.os, 'macos')
@@ -75,7 +78,7 @@ jobs:
           make surge \
             NAUTY=$(brew --prefix nauty)/include/nauty \
             NAUTYLIB=$(brew --prefix nauty)/lib \
-            CCOPT="-O3"
+            CCOPT="${{ matrix.ccopt }}"
 
       - name: Upload artifact
         uses: actions/upload-artifact@v4