yoi/.yoi/tickets/00001KXMK7YMC/resolution.md

Implemented the session-explore-backed extract worker.

The extract worker now receives an immutable SessionReferenceView snapshot and only the builtin:session-explore tool surface. It can search/read bounded evidence, stage one flat candidate per stage_candidate call with resolved source anchors, and finish cleanly with finish_extraction including the no-candidate path.

Validation passed:

• cargo fmt --check
• cargo test -p worker
• cargo test -p memory
• nix build .#yoi
• yoi ticket doctor