SEC Stock Signals endpoints

GET /api/v1/capabilities
GET /api/v1/verdict
GET /api/v1/integrity
GET /api/v1/families?name={slug}
GET /api/v1/ticker/{TICKER}
GET /api/v1/openapi.json
POST /mcp   (optional)

No authentication.
Free: verdict, integrity, families, capabilities.
Paid via Stripe Link in Muse: ticker lookup, $9/month, user must approve the charge.
