GET /connect/pending

OAuth authorization URL for the account owner (valid 10 minutes, single use). Facebook: the owner picks Pages; the result may be a pending connection. WhatsApp: a Postgale page that runs Meta's Embedded Signup (several numbers → pending connection). Telegram has no OAuth: the answer is a one-time code (15 minutes) and instructions: a chat admin adds Postgale's bot as an admin with the right to post and sends /connect <code> in the channel or group (or forwards that channel post to the bot); the chat then appears in GET /accounts and account.connected is emitted. Discord: the owner picks the server and channel on Discord; Postgale stores the channel webhook (one account per webhook; platformAccountId = webhook id). Mastodon needs instance (the server's domain; public DNS names only): Postgale registers itself on that server if needed and the link opens its authorization page (platformAccountId = <id>@<server>). Bluesky has no OAuth: POST {handle, appPassword} (a Bluesky app password, never the account password) connects the account right away and answers {platform, account}; a refused handle or password is a 400. Platforms that are not live on this instance answer 400. Same as GET with externalId (and instance) in the JSON body; Bluesky needs POST with handle and appPassword