feat(tasks): kanban board with To Do / In Progress / Done columns

- add a `status` field to tasks (backend schema/validation/service/types
  + frontend types), kept in sync with the legacy `done` flag
- migration 0017 adds the column and backfills done tasks to "done"
- rewrite the tasks page as a three-column board: per-column add buttons,
  draggable cards, and a status mover in the detail sheet

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

frontend/lib/i18n/locales/en/translation.json

@@ -542,6 +542,16 @@
     "empty": "No tasks here.",
     "markDone": "Mark as done",
     "markNotDone": "Mark as not done",
+    "status": {
+      "todo": "To Do",
+      "in_progress": "In Progress",
+      "done": "Done"
+    },
+    "board": {
+      "addTask": "Add task",
+      "moveTo": "Move to",
+      "emptyColumn": "No tasks."
+    },
     "filters": {
       "all": "All",
       "open": "Open",
@@ -566,6 +576,7 @@
       "due": "Due",
       "duePlaceholder": "e.g. Today",
       "priorityLabel": "Priority",
+      "statusLabel": "Status",
       "cancel": "Cancel",
       "add": "Add task"
     },
@@ -588,7 +599,8 @@
       "patient": "Patient",
       "details": "Details",
       "reopen": "Reopen task",
-      "complete": "Mark complete"
+      "complete": "Mark complete",
+      "moveTo": "Move to"
     },
     "toast": {
       "needSubjectTitle": "Add a subject",

frontend/lib/tasks.ts

@@ -3,6 +3,8 @@ import { apiFetch } from "@/lib/api-client";
 // A care-team task. Mirrors the backend `src/types/task.ts`. Scoped to the active
 // clinic (shared across the care team).
 export type Priority = "high" | "medium" | "low";
+// Board column the task sits in. `done` mirrors `status === "done"`.
+export type TaskStatus = "todo" | "in_progress" | "done";
 
 export type Task = {
   id: string;
@@ -12,6 +14,7 @@ export type Task = {
   assigneeRole: string | null;
   due: string;
   priority: Priority;
+  status: TaskStatus;
   patient: string | null;
   notes: string | null;
   done: boolean;
@@ -28,6 +31,7 @@ export type TaskInput = {
   assigneeRole?: string | null;
   due?: string;
   priority?: Priority;
+  status?: TaskStatus;
   patient?: string | null;
   notes?: string | null;
 };