Add GIF keyboard support via NIP-94

[alltheseas]

Summary

adds a GIF picker to damus compose note view. Options are nostr via nip-94, with fallback to tenor.

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• I have opened or referred to an existing github issue related to this change: Integrated GIF and emojis (100,000 sats) #590
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[alltheseas]

Follow up commit detects manually pasted GIF links in the compose note, and auto adds them to the nostr nip-94 GIF catalog (same outcome as manually picking a GIF from the Tenor tab)

step 1) paste GIF link into compose note

step 2) observe GIF is now part of the nostr GIF selector (post note publication)