List org social/platform accounts

Returns the org's registered accounts (GitHub, Twitter, LinkedIn, etc.) as a paginated list. Pass ?platform=<name> to fetch a single account by platform — returns the account object or null when not set. When the org holds multiple accounts for the platform, single-mode returns the oldest-linked one deterministically; use the full list (omit ?platform) to retrieve them all. The 200 schema is a union of the paginated list (default) or a single OrgAccountItem/null (single-mode) — the OSS CLI depends on the single-row return shape.