fix: show clear error when Cloudflare provider env vars are missing (#20399)

Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>
Co-authored-by: Aiden Cline <aidenpcline@gmail.com>

packages/opencode/src/auth/index.ts

@@ -24,6 +24,7 @@ export namespace Auth {
   export class Api extends Schema.Class<Api>("ApiAuth")({
     type: Schema.Literal("api"),
     key: Schema.String,
+    metadata: Schema.optional(Schema.Record(Schema.String, Schema.String)),
   }) {}
 
   export class WellKnown extends Schema.Class<WellKnown>("WellKnownAuth")({