Add auth type filter (No Auth, API Key, OAuth)

[akuligowski9]

Developers often want to find APIs that don't require authentication first, or specifically need OAuth. Right now you can only filter by category.

Proposed solution
Add filter buttons or a dropdown for auth type alongside the existing category chips.

Auth types in the catalog

• No auth required
• API Key
• OAuth
• X-Mashape-Key

Acceptance criteria

• Auth filter works alongside category filter
• Combinable (e.g. Weather + No Auth)
• Shows count of results