Add L0-L4 security clearance for fleet commands and AI elevation.

Gate manual and AI commands by per-agent clearance, auto-elevate stuck hosts to L4 when AI mode allows, and surface clearance in Access Depth and LOTL timeline.

server/web/src/context/WebSocketProvider.tsx

@@ -184,6 +184,21 @@ export function WebSocketProvider({ children }: { children: React.ReactNode }) {
             }
             break;
           }
+          case 'clearance_elevated': {
+            const p = msg.payload as {
+              agent_id: string;
+              from_level: number;
+              to_level: number;
+              reason?: string;
+              source?: string;
+            };
+            setAgents((prev) =>
+              prev.map((a) =>
+                a.id === p.agent_id ? { ...a, clearance_level: p.to_level } : a,
+              ),
+            );
+            break;
+          }
           case 'new_share': {
             const share = msg.payload as Share;
             setRecentShares((prev) => [share, ...prev].slice(0, 50));