feat(dashboard): operator removal UI for stale machines/sessions (SPEC-004 Task 5)

Admin-only per-row Remove + multi-select bulk removal on the machines view, plus
per-row purge Remove on the sessions view, wired to the Task-5 admin API
(DELETE /api/machines|sessions/:id?purge=true, POST /api/machines/bulk-remove).
Confirm modals (danger-styled, focus-trapped), TanStack refetch so purged rows
leave the console, structured ApiError surfacing, honest partial-bulk summary,
and admin-gating via useAuth().isAdmin as defense-in-depth over the server 403.
Replaces the legacy all-user delete trigger. typecheck/lint/build clean.

Implements specs/v2-stable-identity/plan.md Task 5 (dashboard portion).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

dashboard/src/features/machines/BulkRemoveMachinesDialog.tsx

@@ -0,0 +1,112 @@
+import { ApiError } from "../../api/client";
+import type { BulkRemoveItem } from "../../api/types";
+import { ConfirmDialog } from "../../components/ui/ConfirmDialog";
+import { useToast } from "../../components/ui/toast-context";
+import { useBulkRemoveMachines } from "./hooks";
+
+interface BulkRemoveMachinesDialogProps {
+  /** Selected agent_ids to remove, or empty when the dialog is closed. */
+  agentIds: string[];
+  /** Whether the dialog is open. Kept explicit so an empty list can stay open. */
+  open: boolean;
+  onClose: () => void;
+  /** Called after a successful batch so the page can clear its selection. */
+  onRemoved: () => void;
+}
+
+/** Count outcomes by status for a compact "12 removed, 1 not found" summary. */
+function summarize(results: BulkRemoveItem[]): string {
+  const counts = new Map<string, number>();
+  for (const r of results) counts.set(r.status, (counts.get(r.status) ?? 0) + 1);
+  const order = ["removed", "not_found", "invalid", "error"];
+  const labels: Record<string, string> = {
+    removed: "removed",
+    not_found: "not found",
+    invalid: "invalid",
+    error: "errored",
+  };
+  const parts: string[] = [];
+  for (const status of order) {
+    const n = counts.get(status);
+    if (n) parts.push(`${n} ${labels[status] ?? status}`);
+  }
+  // Surface any unexpected status the server may add in the future.
+  for (const [status, n] of counts) {
+    if (!order.includes(status)) parts.push(`${n} ${status}`);
+  }
+  return parts.join(", ");
+}
+
+/**
+ * Confirm + bulk-remove the selected machines (Task 5). On confirm the selected
+ * agent_ids are purged in one request; the per-id summary the server returns is
+ * surfaced as a toast (e.g. "12 removed, 1 not found") so a partial outcome is
+ * visible rather than silently swallowed.
+ */
+export function BulkRemoveMachinesDialog({
+  agentIds,
+  open,
+  onClose,
+  onRemoved,
+}: BulkRemoveMachinesDialogProps) {
+  const toast = useToast();
+  const bulkRemove = useBulkRemoveMachines();
+  const count = agentIds.length;
+
+  function onConfirm() {
+    if (count === 0) {
+      onClose();
+      return;
+    }
+    bulkRemove.mutate(agentIds, {
+      onSuccess: (res) => {
+        const summary = summarize(res.results);
+        if (res.removed === res.requested) {
+          toast.success(
+            `Removed ${res.removed} ${res.removed === 1 ? "machine" : "machines"}`,
+            summary || undefined,
+          );
+        } else {
+          // Partial: some ids were not found / invalid. Report as info, not an
+          // error — the requested removals that could happen, did.
+          toast.info(
+            `Removed ${res.removed} of ${res.requested}`,
+            summary || undefined,
+          );
+        }
+        onRemoved();
+        onClose();
+      },
+      onError: (err) => {
+        toast.error(
+          "Could not remove machines",
+          err instanceof ApiError
+            ? `${err.message}${err.code ? ` (${err.code})` : ""}`
+            : "The server did not respond. No machines were removed.",
+        );
+      },
+    });
+  }
+
+  return (
+    <ConfirmDialog
+      open={open}
+      title={`Remove ${count} ${count === 1 ? "machine" : "machines"}?`}
+      danger
+      busy={bulkRemove.isPending}
+      confirmLabel={`Remove ${count}`}
+      cancelLabel="Keep machines"
+      onConfirm={onConfirm}
+      onCancel={onClose}
+      body={
+        <p style={{ marginTop: 0 }}>
+          Remove the {count} selected{" "}
+          {count === 1 ? "machine" : "machines"} from the GuruConnect console.
+          Their live sessions are dropped and the rows disappear from the list.
+          Any that are genuinely still in service re-appear when their agents
+          next check in.
+        </p>
+      }
+    />
+  );
+}