Prepare source provenance for your adoption intent [write]

Requires an unrestricted personal owner write bearer or a platform-issued agent-use-web consumer bearer. Read-only, restricted, team, app, task, fixed-workspace and workspace-identity credentials are refused. Read and proof operations also require write scope. Ownership comes from the actual bearer and exactly one consumer identity mapping, never an input owner or email. The target stays inactive: no content is copied, no revision is committed and no writer is activated. Requires the actual source publisher, not a collaborator. Binds the concrete target/request and current content/sharing snapshot under the existing source writer lock. Existing pending bindings cannot be stolen; retire and cancel first. Normal content and sharing writers remain available and invalidate old proofs.