[EricWittmann]

Fixes #227.

• History entries record a single arrival edge, so at an AND-join only the last-arriving branch's edge was highlighted. New traversedEdgeIds (utils/parallelView.ts) adds every incoming edge of a join that has fired, plus edges of branches waiting in instance.joinArrivals.
• The Viewer now runs analyzeParallelRegions and passes parallelRole to nodes, so Fork/Join badges render as in the Editor.

Assumes the Axiom runtime uses the same AND-join semantics as analyzeParallelRegions.

[EricWittmann]

Verified the AND-join assumption against the runtime: Axiom executes via apitomy-flow-engine, whose ParallelRegions.java is mirrored line-for-line by parallelRegions.ts (same fork rule, same priority-ordered BFS join selection, same required incoming-edge set), and WorkflowEngine.moveBranch fires the join only when all incoming edges have arrived, recording a single history entry. So inferring all incoming join edges from a fired join is exact.

Caveat: Axiom does not currently pass joinArrivals to the viewer (hard-coded {}), so waiting-branch edges in live runs won't highlight there until Apitomy/apitomy-axiom#513 is done. Completed/past-join runs are fully fixed by this PR.