Organization ticket digest: email client contacts their organization's open tickets

🔍 Problem Statement

As a client contact, I can't see my organization's open support tickets in one place, so I chase status updates ticket by ticket.

As a client contact, I want a scheduled email listing my organization's open tickets and their status, so that my team knows where every request stands.
As a support admin, I want to send that email from an Automation targeting a customer segment, so that adding a contact to an organization enrolls them.

Audience

Given an Automation with only the Send email action, when an admin picks customer segments as its audience, then it saves without the Creation action.
Given that Automation runs, when recipients are selected from its customer segments, then each matching customer gets one email and no subscription is created.
Given the customer segment builder, when an admin adds an Organization criterion (has any organization, or is one of selected organizations), then only matching customers are included.

Email content

Given an email containing {{organization.open_tickets}}, when it is sent, then it lists the recipient's organization's unsolved tickets on the Automation's site with ID, subject, status and last activity.
Given any listed ticket, when it is rendered, then its status reads Open (New, Active, On hold) or Awaiting your reply (Pending).
Given a ticket subject containing markdown or HTML, when it is listed, then it renders as plain text.
Given an email containing {{organization.name}}, when it is sent, then it shows the recipient's organization name.
Given a recipient whose organization has no unsolved tickets, when the Automation runs, then [decision: skip their email, or send a "no open tickets" message].

Ticket linking

Given unlinked tickets opened from an email address, when a customer with that address is created on the same site, then those tickets link to the new customer.
Given existing unlinked tickets, when the one-time backfill runs, then every ticket whose first inbound sender matches a customer on its site is linked to that customer.
Given a ticket in the dashboard, when an agent picks a customer in the ticket details, then the ticket links to that customer, including re-linking a wrong match.
Given a request that sets a ticket's customer, when it is saved, then only a customer on the ticket's site is accepted.
Given a customer who moves to another organization, when the digest runs, then [decision: their past tickets stay with the old organization, or move with them].

Security and API

Given a visitor registering through the SDK on the support site [decision: or every Ticket Center site], when they enter an existing organization's name, then they are not added to it.
Given the new Core API endpoint for linking a ticket to a customer, when it is released, then it is documented on docs.pelcro.com and covered by automated tests.
This change will impact the UI and API, specifically Automations (campaign form and Initiate job), customer segments, the email variable catalog, ticket linking and SDK registration.
This solution will include the following limitations: weekly read-only snapshot; no replies or new tickets from the digest; unsolved tickets only; one organization per contact; contacts must be customers on the support site, loaded separately through the Core API; no Core API for creating Automations or segments.