feat(ui): Data Flow tab — live lineage graph + PII overlay + movement triggers

New DataFlowView (topology-style): nodes positioned from /api/dataflow with
measured-anchor SVG edges and animated particles (active CDC + running
movements). PII overlay shows shield badges + per-column detail inspector.
Bottom strip triggers ETL movements and toggles the ETL agent. Wired into
SideNav (Data Flow) and App routing; added types + api helpers.

ui/src/App.tsx

@@ -19,6 +19,7 @@ import { StorageView } from './components/features/StorageView'
 import { HdfsView } from './components/features/HdfsView'
 import { DataGenView } from './components/features/DataGenView'
 import { ChangesView } from './components/features/ChangesView'
+import { DataFlowView } from './components/features/DataFlowView'
 import { SearchView } from './components/features/SearchView'
 import { SshTerminal } from './components/features/SshTerminal'
 import { TerminalDock } from './components/features/TerminalDock'
@@ -131,6 +132,8 @@ export default function App() {
                   <DataGenView onPulse={cc.pulseFlow} onOpenPlatform={() => cc.setMainView('platform')} />
                 ) : cc.mainView === 'changes' ? (
                   <ChangesView liveChanges={cc.changes} />
+                ) : cc.mainView === 'dataflow' ? (
+                  <DataFlowView />
                 ) : cc.mainView === 'presentation' ? (
                   <PresentationView />
                 ) : cc.mainView === 'dataquality' ? (