test: stabilize suite and broaden integration coverage (#32)

* tests: cache integration/report fixtures to speed up tests

* fix: speed up yearly aggregation and refresh timings report

* chore: remove the report

* fix: unrecognized named-value: 'runner'. Located at position 1 within expression: runner.temp

* fix: ruff linting error

* test: strengthen assertions and stabilize tests

* test(integration): expand rendered chart metrics

.github/workflows/test.yml

@@ -35,6 +35,11 @@ jobs:
       - name: Install dependencies
         run: uv sync --locked --extra dev
 
+      - name: Set up matplotlib cache
+        run: |
+          echo "MPLCONFIGDIR=$RUNNER_TEMP/matplotlib" >> "$GITHUB_ENV"
+          mkdir -p "$RUNNER_TEMP/matplotlib"
+
       - name: Run tests with coverage
         run: |
           uv run pytest \