feat(realism-ui): operator panel for planner weights + canary probability

New /realism-config page sits next to Persona Generation and
Synthetic Files under the Automation nav. Editable weight tables for
user / system / canary content classes (with live percent share),
plus a slider for canary_probability.

Wires GET/PUT /api/v1/realism/config — viewer can read; admin
required to save. Validation errors from the API are surfaced inline
rather than swallowed; the SAVE button refreshes from the server's
canonical snapshot so the operator sees exactly what landed (matters
because cross-list entries are silently dropped server-side).

decnet_web/src/App.tsx

@@ -26,6 +26,7 @@ const CampaignDetail = lazy(() => import('./components/CampaignDetail'));
 const Orchestrator   = lazy(() => import('./components/Orchestrator'));
 const PersonaGeneration = lazy(() => import('./components/PersonaGeneration'));
 const SyntheticFiles = lazy(() => import('./components/SyntheticFiles/SyntheticFiles'));
+const RealismConfig = lazy(() => import('./components/RealismConfig/RealismConfig'));
 const CanaryTokens   = lazy(() => import('./components/CanaryTokens'));
 const TopologyPersonaGeneration = lazy(() =>
   import('./components/PersonaGeneration').then((m) => ({ default: m.TopologyPersonaGeneration })),
@@ -131,6 +132,7 @@ const AuthedShell: React.FC<AuthedShellProps> = ({ onLogout, onSearch, searchQue
             <Route path="/orchestrator" element={<Orchestrator />} />
             <Route path="/persona-generation" element={<PersonaGeneration />} />
             <Route path="/synthetic-files" element={<SyntheticFiles />} />
+            <Route path="/realism-config" element={<RealismConfig />} />
             <Route path="/canary-tokens" element={<CanaryTokens />} />
             <Route path="/topologies/:id/personas" element={<TopologyPersonaGeneration />} />
             <Route path="/config" element={<Config />} />