feat(web): Orchestrator page + SSE hook + AUTOMATION nav group

New /orchestrator route. Paginated read-only event list with kind
filter (all|traffic|file), pause-stream toggle, in-window failure
badge ('X failures / 1h'), and an SSE-driven 'live' status pill.
Streamed rows prepend on top up to a 500-row in-memory cap.

Sidebar gains an AUTOMATION nav group; Orchestrator is the first
child. Future workers (mutator/prober activity) plug in as siblings.

decnet_web/src/App.tsx

@@ -23,6 +23,7 @@ const Identities    = lazy(() => import('./components/Identities'));
 const IdentityDetail = lazy(() => import('./components/IdentityDetail'));
 const Campaigns     = lazy(() => import('./components/Campaigns'));
 const CampaignDetail = lazy(() => import('./components/CampaignDetail'));
+const Orchestrator   = lazy(() => import('./components/Orchestrator'));
 const Config         = lazy(() => import('./components/Config'));
 const Bounty         = lazy(() => import('./components/Bounty'));
 const Credentials    = lazy(() => import('./components/Credentials'));
@@ -121,6 +122,7 @@ const AuthedShell: React.FC<AuthedShellProps> = ({ onLogout, onSearch, searchQue
             <Route path="/identities/:id" element={<IdentityDetail />} />
             <Route path="/campaigns" element={<Campaigns />} />
             <Route path="/campaigns/:id" element={<CampaignDetail />} />
+            <Route path="/orchestrator" element={<Orchestrator />} />
             <Route path="/config" element={<Config />} />
             <Route path="/swarm-updates" element={<RemoteUpdates />} />
             <Route path="/swarm/hosts" element={<SwarmHosts />} />