Fix: Remove x86-64-v3 CPU flags for broader compatibility

The -march=x86-64-v3 flag requires AVX2 instructions which are not
available on all target machines (e.g. QEMU VMs with only SSE4.2).
This caused 'Illegal instruction' crashes at runtime.

Remove the explicit -march flags from both build and release workflows
to use the default target architecture, ensuring the .deb package runs
on a wider range of x86-64 machines.

.gitea/workflows/build.yml

@@ -74,10 +74,7 @@ jobs:
       - name: Configure (CMake)
         shell: bash
         run: |
-          # Use conda Clang with modern CPU optimizations
-          pixi run cmake --preset conda-linux-release \
-            -DCMAKE_C_FLAGS="-march=x86-64-v3" \
-            -DCMAKE_CXX_FLAGS="-march=x86-64-v3"
+          pixi run cmake --preset conda-linux-release
 
       - name: Build
         run: pixi run cmake --build build/release -j$(nproc)

.gitea/workflows/release.yml

@@ -23,9 +23,8 @@ jobs:
       CCACHE_SLOPPINESS: "include_file_ctime,include_file_mtime,pch_defines,time_macros"
       BUILD_TAG: ${{ github.ref_name || inputs.tag }}
       MAKE_INSTALLER: "true"
-      # Modern CPU flags for x86-64-v3 (AVX, AVX2, BMI1, BMI2, F16C, FMA, LZCNT, MOVBE, XSAVE)
-      CFLAGS: "-march=x86-64-v3 -O3"
-      CXXFLAGS: "-march=x86-64-v3 -O3"
+      CFLAGS: "-O3"
+      CXXFLAGS: "-O3"
 
     steps:
       - name: Trust FreeIPA CA certificate