test(web): add unit tests for decision graph transformations master
Tests the pure functions from decision-graph.ts: - decisionsToElements: converts GraphNode/GraphEdge to Cytoscape elements - filterNowMode: filters for active decisions and chosen options only - decisionStylesheet: generates Cytoscape styling rules Coverage: - P4f.AC2.1: Decision nodes render as diamonds with gold color - P4f.AC2.2: Option nodes render as hexagons (chosen=green, rejected=gray) - P4f.AC2.3: Outcome and revisit nodes with distinct shapes and colors - P4f.AC2.4: Edge labels show relationship types - P4f.AC3.1: Now mode includes only active/decided decisions, chosen options - P4f.AC3.2: History mode includes full evolution with rejected/abandoned nodes - Edge case handling: empty input arrays, endpoint filtering, realistic scenarios 27 tests total, all passing. Verifies complete decision graph transformation pipeline. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>