X (Twitter) Integration

[JoaquinBN]

X/Twitter integration for the Community section. Includes OAuth for account linking, post contributions with reach-based points, and ownership verification.

• Implement X OAuth flow (part of onboarding?)
• Link X account to user profile
• Create X post contribution type
• Define X reach metrics for evaluation (engagement, impressions, followers — needs decision)
• Implement X post ownership verification (post URL author matches linked X account)
• Display X connection status on profile