feat: centralize JavaScript lint workflows

[vitormattos]

Summary

Continue #15 by centralizing the ESLint and stylelint workflows behind reusable implementations with thin catalog callers.

The callers are pinned to immutable commit 28874b9141c73178d13aae163503d673d52df5a8.

LibreCode adaptations

Compared with the current Nextcloud templates:

• use public ubuntu-latest;
• update checkout/setup-node/path-filter actions to current pinned SHAs;
• avoid installing a PR-controlled npm range globally;
• use the npm bundled with the selected Node runtime and enable engine-strict;
• pass summary values through environment variables instead of direct shell interpolation;
• preserve the existing final check names (eslint and stylelint).

After merge, both workflows can be validated in LibreCodeCoop/extract.