Define data export and portability guarantees

[zaridan]

Define Helpthread's data export and portability guarantees.

Why:

Operator ownership is not credible unless an operator can leave, back up, inspect, and move their data without relying on Helpthread or Resonant IQ.

Scope:

• conversations
• messages/threads
• participants/customers
• attachments/blob references
• mailboxes and provider metadata
• tags/status/assignment/history
• events/provenance
• Relay and Agent Exchange records when present

Acceptance:

• Document the minimum export formats Helpthread should support.
• Define which data belongs in database export, blob export, and higher-level portable export.
• Define how attachments are referenced or bundled.
• Define what secrets/tokens are intentionally excluded from export.
• Define how exported records preserve provenance and conversation history.
• Document the operator's backup/restore/export responsibilities on Vercel/Supabase.
• Add follow-up implementation issues if the current product cannot satisfy the defined guarantees.