Audit Trail and K-1 fan-out via identity graph

**Audit Trail** (Audit Trail tab) is the immutable record of every change to every line item: who, when, prior value, new value, and (if known) the source of the change (manual edit / sync from books / Wally action). The trail cannot be edited or deleted; it can only be appended to. It's the single most important thing if your return ever gets examined.

**K-1 fan-out** (pass-through entities only — Partnership, S-Corp):
- When you mark a return as final, the platform generates a K-1 for every owner/partner from the partner list
- Each K-1 is delivered to the recipient via the identity graph — appears in their /me/tax inbox at the right tax year
- If a partner has multiple Turtini identities (work email + personal email), the identity graph resolves to the canonical user — no duplicate delivery
- If a partner is not yet on Turtini, the K-1 is held with an invitation. When they sign up with a matching email, they get it.
- The K-1 PDF is rendered with a Verified-by-Turtini stamp + SHA-256 of the line items, so the recipient can prove what they received matches what was issued