Adds a new "rBudgets" sub-tab to rFlows where participants allocate
budgets across departments via sliders, with a collective SVG pie chart
showing aggregated results. Includes schema v4 migration, budget CRUD
API routes, demo seed data (5 segments, 4 participants, $500k pool),
and slider auto-normalization to 100%. Removes redundant "Flows" and
"Flow Viewer" entries from outputPaths/subPageInfos.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>