The indexer's first views of manifests, modules and graph are replaced by one meshcatalogclient.Catalog per watched branch
(the trunk's from the start, each branch a registration names from then on); the world keeps each branch's modules, graph nodes
and manifests, and a pass splits a module's nodes by the branch their placements name and computes each group's wants from that
branch's half. Not built: AC2 (a composition step on beta only), which is AS5's step.
Builds: design 47 G §14, §184, §191, §194, §195
Tests: TestACommitOnBetaMovesOnlyTheNodeThatChoseBeta (failed with the groups on the trunk alone), TestTheCatalogHalfIsTakenInPerBranch
Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ
jschoubben
846340c553