chore: bump actions, reflow configs, fix examples

Bump codecov/codecov-action to v7 and docker/metadata-action
to v6 in the CI and release workflows.

Reflow .golangci.yml and html_styles.css under
the prettier plugin dprint now loads.

Exporter examples hand their export to the temp-dir helper instead of
pairing defer cleanup with log.Fatal. log.Fatal exits the process, so
the deferred cleanup never ran and a failed export left its temp dir
behind. gocritic reported it as exitAfterDefer.

.github/workflows/ci.yml

@@ -286,7 +286,7 @@ jobs:
           } >> "$GITHUB_STEP_SUMMARY"
 
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@v7
         with:
           files: ./coverage/coverage.out
           flags: Go ${{ env.GO_VERSION }}
@@ -401,7 +401,7 @@ jobs:
 
       - name: Extract metadata
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: |
             ${{ env.IMAGE_NAME }}