Fix featured activities filters

[bernardhanna]

Summary

• Replace Vue select-field with native <select wire:model.live> so month/language changes actually re-query
• Stop language filter from silently falling back to all events when nothing matches
• Default language to “All Languages”
• Keep listing all approved upcoming open-online events

Why

Users saw one activity repeated for every month, and language filtering appeared broken.

Test plan

• Open /featured-activities
• Switch months and confirm different events appear for each month that has activities
• Switch language and confirm the list filters (empty state if none match)
• Confirm October (and other months with data) show multiple open-online events when present

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