add Gitea Actions workflow for C++ tests

Runs conformallab_tests (GTest) on every push to main/dev/claude/**
using ubuntu-latest + cmake + g++. Only the test binary is built,
not the full app (no CGAL/Boost compilation needed).

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

.gitea/workflows/cpp-tests.yml

@@ -0,0 +1,37 @@
+name: C++ Tests
+
+on:
+  push:
+    branches:
+      - main
+      - dev
+      - "claude/**"
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install build tools
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends \
+            cmake \
+            g++ \
+            git \
+            ca-certificates
+
+      - name: Configure (Release, tests enabled)
+        run: |
+          cmake -S code -B build \
+            -DCMAKE_BUILD_TYPE=Release \
+            -DBUILD_TESTING=ON
+
+      - name: Build test binary
+        run: cmake --build build --target conformallab_tests -j$(nproc)
+
+      - name: Run tests
+        run: ctest --test-dir build -R conformallab_tests --output-on-failure