List Conversion Actions

The account's conversion actions, with the id + label a tag install needs — parsed from Google's own event snippet, so nobody has to know what a "conversion label" is, let alone paste one.

Every action is returned with installable and, when it is not, a blocked_reason saying why. The four UI panels used to filter on conversion_id && conversion_label themselves, which silently dropped every imported, call-only and app conversion — real, enabled conversions that simply have no website snippet — and then blamed the sync.

synced separates "we have never pulled this account" from "this account genuinely has no conversion actions". They are different problems with different answers, and both used to render the same sentence.