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/db/schema/tasks.ts

@@ -22,6 +22,9 @@ export const tasks = pgTable(
       .references(() => organization.id, { onDelete: "cascade" }),
     title: text("title").notNull(),
     assignee: text("assignee").notNull().default("Unassigned"),
+    // The department (member role) a task is assigned to, e.g. "reception".
+    // Null means a personal task belonging to its creator. Drives who sees it.
+    assigneeRole: text("assignee_role"),
     due: text("due").notNull().default("No due date"),
     priority: text("priority").$type<TaskPriority>().notNull(),
     patient: text("patient"),
@@ -30,6 +33,9 @@ export const tasks = pgTable(
     createdBy: text("created_by").references(() => user.id, {
       onDelete: "set null",
     }),
+    // Denormalised creator name so "created by …" survives even if the user is
+    // later removed (createdBy is set null on delete).
+    createdByName: text("created_by_name"),
     createdAt: timestamp("created_at").defaultNow().notNull(),
     updatedAt: timestamp("updated_at")
       .defaultNow()