ci: add pytest --maxfail=1 and simple pip/venv cache at /cache if available

.forgejo/workflows/ci.yml

@@ -65,11 +65,33 @@ jobs:
       - name: Set up venv and install deps
         run: |
           set -euo pipefail
-          python3 -m venv .venv
+          # Prefer persistent cache if runner provides /cache
+          USE_CACHE=0
+          if [ -d /cache ] && [ -w /cache ]; then
+            export PIP_CACHE_DIR=/cache/pip
+            mkdir -p "$PIP_CACHE_DIR"
+            REQ_HASH=$(sha256sum requirements.txt | awk '{print $1}')
+            PYVER=$(python3 -c 'import sys;print(".".join(map(str, sys.version_info[:2])))')
+            CACHE_VENV="/cache/venv-${REQ_HASH}-py${PYVER}"
+            if [ -d "$CACHE_VENV" ]; then
+              echo "Using cached virtualenv: $CACHE_VENV"
+              ln -s "$CACHE_VENV" .venv
+              USE_CACHE=1
+            else
+              echo "Creating cached virtualenv: $CACHE_VENV"
+              python3 -m venv "$CACHE_VENV"
+              ln -s "$CACHE_VENV" .venv
+            fi
+          fi
+
           . .venv/bin/activate
           python -m pip install --upgrade pip
-          pip install -r requirements.txt
-          pip install pytest
+          if [ "$USE_CACHE" = "1" ]; then
+            # Ensure required packages are present; pip will use cache
+            pip install -r requirements.txt pytest || pip install -r requirements.txt pytest
+          else
+            pip install -r requirements.txt pytest
+          fi
 
       - name: Format check (black)
         run: |
@@ -84,7 +106,7 @@ jobs:
       - name: Run tests (pytest)
         run: |
           . .venv/bin/activate
-          pytest -q
+          pytest -q --maxfail=1
 
       - name: Build sample reports (no artifact upload)
         run: |