fix: clinic creation gating, analysis line charts, username + task assignee, delete confirm

- Hide "Create clinic" (sidebar footer) for non-admins; only owner/admin can
  spin up additional clinics. Onboarding for brand-new users is unaffected.
- Analysis: drop the bar charts; show line charts (Sparkline) inside KPI cards
  that open a detail dialog with the full chart + per-point breakdown.
- Add Team Member: validate the username client-side (no spaces; letters,
  numbers, dots, underscores) with a clear warning + field hint.
- Tasks: New Task now has an Assignee selector (Myself / Other → department).
  Tasks are visible to the department they're assigned to (or the creator), and
  show who created them. Backend adds assignee_role + created_by_name with
  visibility filtering in listTasks; owners/admins see all.
- Care team: removing a member now asks for confirmation first (dialog) and
  surfaces success/failure + refreshes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/types/task.ts

@@ -7,11 +7,15 @@ export type Task = {
   id: string;
   title: string;
   assignee: string;
+  // Department (member role) the task is assigned to; null = personal task.
+  assigneeRole: string | null;
   due: string;
   priority: TaskPriority;
   patient: string | null;
   notes: string | null;
   done: boolean;
+  createdById: string | null;
+  createdByName: string | null;
   createdAt: string;
   updatedAt: string;
 };