Add fleet registry removal with confirm modal and agent_removed WS.

Operators can remove machines from Crucible and dashboard rosters with honest messaging that deletion is registry-only; bulk select, oath ledger entries, and Go/Vitest coverage included.

server/web/src/components/Fleet/FleetToolbar.tsx

@@ -125,15 +125,19 @@ export default function FleetToolbar({
           <button type="button" className="btn btn-outline btn-sm" disabled={bulkBusy || !selectedAgents.some((a) => a.status === 'online')} onClick={() => onBulkAction('resume')} title="Fleet health: restore hashing">Resume</button>
           <button type="button" className="btn btn-outline btn-sm" disabled={bulkBusy || !selectedAgents.some((a) => a.status === 'online')} onClick={() => onBulkAction('stop')}>Stop</button>
           <button type="button" className="btn btn-outline btn-sm" disabled={bulkBusy || !selectedAgents.some((a) => a.status === 'online')} onClick={() => onBulkAction('restart_idle')}>Restart idle</button>
-          <button
-            type="button"
-            className="btn btn-sm"
-            disabled={bulkBusy}
-            style={{ background: 'rgba(255,40,40,0.15)', border: '1px solid #ff4444', color: '#ff6666' }}
-            onClick={() => onBulkAction('delete')}
-          >
-            🗑 Delete selected
-          </button>
+          <span style={{ display: 'inline-flex', alignItems: 'center', gap: '0.25rem' }}>
+            <button
+              type="button"
+              className="btn btn-sm"
+              disabled={bulkBusy}
+              style={{ background: 'rgba(255,40,40,0.15)', border: '1px solid #ff4444', color: '#ff6666' }}
+              onClick={() => onBulkAction('delete')}
+              title="Remove selected machines from fleet registry — does not uninstall on host"
+            >
+              Remove from fleet
+            </button>
+            <HelpTip field="fl_delete_roster" />
+          </span>
         </div>
       )}
     </div>