#259 docs(social): credit pricing (5 + posts) + auth on scrape endpoints

Summary

Contract PR for the credit-gate item on recoupable/chat#1836 (pricing per the cost research). Merge before the api PR.

• Both scrape endpoints: "Costs 5 credits, plus 1 credit per post requested via posts" (bulk: per social profile scraped).
• Both: new 402 response, schema mirroring ResearchInsufficientCreditsResponse (matches buildInsufficientCreditsResponse exactly: error/remaining_credits/required_credits/checkoutUrl/declineReason?).
• POST /api/artist/socials/scrape: adds security (apiKeyAuth/bearerAuth) + 401/403 responses — the endpoint gains auth in the api PR (it currently has none, flagged in the credits audit).

Verification

Both OpenAPI files re-parse; diff is additive.

🤖 Generated with Claude Code

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Summary by cubic

Moved social scrape pricing to credits.mdx (5 credits + 1 per posts per profile) and documented credit-gating and auth. Both scrape endpoints now include 402 insufficient-credits responses; POST /api/artist/socials/scrape adds API-key/Bearer auth with 401/403.

• Migration
  • Handle HTTP 402 from both endpoints; use checkoutUrl to guide top-ups.
  • For POST /api/artist/socials/scrape, include API key or Bearer token and handle 401/403.