A supported way to transform model fields on write and read (encrypt / tokenize / redact)

Summary Add a small, opt-in registration point that lets a plugin transform selected model attributes on the way into Postgres and on the way back out, without editing the model classes. Declare which attributes a transformer owns, and Chatwoot applies it in the write path and the read path, passing the current request's agent so the transform can be role-aware. This is the seam for field-level encryption, tokenization, and role-based PII redaction of contacts and messages. It is deliberately vendor-neutral: the framework ships the registration point, not any particular crypto or provider. Motivation A support desk holds the data a breach is about: contact names, phone numbers, emails, and the full text of conversations. A growing number of self-hosted operators want some of those columns to be ciphertext at rest, or tokenized for compliance scope reduction, or redacted for agents without a role, while Chatwoot keeps working with plaintext in-request. Today there is n…