feat(frontend): My Reviews queue, duplicate-test badge, tactic order, legend + tooltip fixes

- TestsPage gains a "My Reviews" toggle for red_lead/blue_lead, separate
  from "My Tasks" — filters by reviewer_id at the red_review/blue_review
  gate instead of the unrelated in_review validation stage
- Test Catalog cards now warn when a technique already has existing
  tests, using the backend's new existing_test_count
- ExecutiveDashboardPage drops its duplicate client-side tactic-order
  sort now that the backend returns canonical order; time-range filter
  now notes which sections it actually scopes
- HeatmapLegend adds the missing review_required swatch (as an overlay
  indicator, matching how it's actually rendered on cells) and hover
  tooltips reusing StatusBadge's copy instead of being unexplained
  static color chips
- Fix a real React key bug in ControlsTable: rows were grouped in a
  keyless shorthand fragment, which can misreconcile when the table is
  filtered/sorted; switched to a keyed Fragment
- Minor: CompliancePage summary-card grid no longer strands a lone card
  on tablet widths

frontend/src/api/tests.ts

@@ -70,6 +70,8 @@ export interface TestListFilters {
   platform?: string;
   created_by?: string;
   pending_validation_side?: "red" | "blue";
+  /** "My reviews" queue — tests assigned to this reviewer at the red_review/blue_review gate. */
+  reviewer_id?: string;
   not_in_any_campaign?: boolean;
   assigned_to_me?: boolean;
   unassigned_red?: boolean;
@@ -88,6 +90,7 @@ export async function getTests(filters?: TestListFilters): Promise<Test[]> {
   if (filters?.platform) params.append("platform", filters.platform);
   if (filters?.created_by) params.append("created_by", filters.created_by);
   if (filters?.pending_validation_side) params.append("pending_validation_side", filters.pending_validation_side);
+  if (filters?.reviewer_id) params.append("reviewer_id", filters.reviewer_id);
   if (filters?.not_in_any_campaign) params.append("not_in_any_campaign", "true");
   if (filters?.offset !== undefined) params.append("offset", String(filters.offset));
   if (filters?.limit !== undefined) params.append("limit", String(filters.limit));