feat(home): add Recently Responded sort and i18n the Pending filter

[lol2x]

Summary

• New sort option Recently Responded in the home page sort dropdown — orders posts by response_date (when an admin last changed status), newest first.
• Filters out posts with response_date IS NULL so the sort stays meaningful regardless of the active status filter. Without this, picking the new sort while the default Open/Started/Planned filter is active produces a long tail of unresponded posts in arbitrary order.
• i18n the Pending status filter (collaborator/admin only) and the inline "pending" badge in ListPosts — both were previously hardcoded English.
• Adds Polish translations for the two new keys plus the previously-untranslated Pending key.

Why

Admins/collaborators often want to review what's been recently dealt with — completions, declines, planned items — without having to also remember to flip the sort manually. Sorting by id/creation date doesn't surface this; the existing per-status planned/completed/declined views are deprecated in favor of status filters but those don't carry the response-date sort. This stitches that gap.

Behavior

• Pairs naturally with a Completed + Declined status filter to get a chronological "what got done" feed.
• With default filters, the IS NOT NULL guard means only posts that have ever been responded to appear (e.g. a post reopened after being marked complete still shows because its response_date is preserved).
• Filter and sort remain independent — picking this sort doesn't override your status selection.