ink.branchline.publishBud

Publish a new bud. The parent may be another bud (continuation) or a seed (planting a root bud). The caller must be signed in. The AppView writes an ink.branchline.bud record to the caller's PDS and mirrors it into the local read cache so the new bud is immediately navigable. Rejection reasons mirror ink.branchline.bud create validation — 500-word limit on `text`, 24h parent growing window, self-reply, seed chain/expiry/grantee checks, etc.