Merge tasks into notes: a task is just a note with task attributes

A task is now a note with status/priority/due_date columns set (status IS NOT NULL).
This eliminates the separate tasks table, companion note system, cascade deletes,
bidirectional title sync, and _skip_cascade flags.

Migration (0004):
- Add status, priority, due_date columns to notes table
- Migrate task data from companion notes and orphan tasks
- Drop tasks table and old enum types

Backend:
- models/note.py: Add TaskStatus/TaskPriority enums, task columns, is_task property
- models/task.py: Deleted (merged into note.py)
- models/__init__.py: Re-export enums from note.py, remove Task import
- services/notes.py: Remove companion/cascade logic, add is_task filter,
  convert_note_to_task, convert_task_to_note, simplified backlinks
- services/tasks.py: Rewritten as thin wrappers around notes service
- routes/notes.py: Add is_task filter (default false), task fields in CRUD,
  convert-to-note endpoint
- routes/tasks.py: description→body (with fallback), remove note_id filter

Frontend:
- types/note.ts: Add TaskStatus, TaskPriority, task fields to Note interface
- types/task.ts: Task is now a re-export alias for Note
- stores/notes.ts: Simplify convertToTask, add convertToNote
- stores/tasks.ts: description→body in createTask/updateTask
- TaskEditorView: description→body, remove companion note UI
- TaskViewerView: description→body, remove companion note link, add Convert to Note
- NoteViewerView: Remove companion task UI, simplify convert-to-task
- TaskCard: description→body, non-null assertions for status/priority

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/NoteViewerView.vue

@@ -4,25 +4,20 @@ import { useRoute, useRouter } from "vue-router";
 import { useNotesStore } from "@/stores/notes";
 import { renderMarkdown } from "@/utils/markdown";
 import { relativeTime } from "@/composables/useRelativeTime";
-import { apiGet, apiPost } from "@/api/client";
-import type { Task, TaskListResponse, TaskStatus } from "@/types/task";
+import { apiPost } from "@/api/client";
 import type { Note } from "@/types/note";
 import TagPill from "@/components/TagPill.vue";
-import StatusBadge from "@/components/StatusBadge.vue";
 
 const route = useRoute();
 const router = useRouter();
 const store = useNotesStore();
 const bodyEl = ref<HTMLElement | null>(null);
-const linkedTasks = ref<Task[]>([]);
 const backlinks = ref<{ type: string; id: number; title: string }[]>([]);
 const converting = ref(false);
 
 const noteId = computed(() => Number(route.params.id));
-const hasCompanionTask = computed(() => linkedTasks.value.length > 0);
 
 async function loadNote(id: number) {
-  linkedTasks.value = [];
   backlinks.value = [];
   await store.fetchNote(id);
 
@@ -32,16 +27,10 @@ async function loadNote(id: number) {
     return;
   }
 
-  // Fetch tasks linked to this note & backlinks in parallel
-  const [taskData, backlinkData] = await Promise.allSettled([
-    apiGet<TaskListResponse>(`/api/tasks?note_id=${id}`),
-    store.fetchBacklinks(id),
-  ]);
-  if (taskData.status === "fulfilled") {
-    linkedTasks.value = taskData.value.tasks;
-  }
-  if (backlinkData.status === "fulfilled") {
-    backlinks.value = backlinkData.value;
+  try {
+    backlinks.value = await store.fetchBacklinks(id);
+  } catch {
+    backlinks.value = [];
   }
 }
 
@@ -93,37 +82,14 @@ function onTagClick(tag: string) {
   router.push({ path: "/notes", query: { tag } });
 }
 
-const statusCycle: Record<TaskStatus, TaskStatus> = {
-  todo: "in_progress",
-  in_progress: "done",
-  done: "todo",
-};
-
-async function toggleTaskStatus(task: Task) {
-  const newStatus = statusCycle[task.status];
-  try {
-    const { apiPatch } = await import("@/api/client");
-    const updated = await apiPatch<Task>(
-      `/api/tasks/${task.id}/status`,
-      { status: newStatus }
-    );
-    const idx = linkedTasks.value.findIndex((t) => t.id === task.id);
-    if (idx !== -1) {
-      linkedTasks.value[idx] = updated;
-    }
-  } catch {
-    // silently fail
-  }
-}
-
 async function convertToTask() {
   if (converting.value) return;
   converting.value = true;
   try {
-    const task = await store.convertToTask(noteId.value);
+    await store.convertToTask(noteId.value);
     const { useToastStore } = await import("@/stores/toast");
     useToastStore().show("Converted to task");
-    router.push(`/tasks/${task.id}`);
+    router.push(`/tasks/${noteId.value}`);
   } catch {
     const { useToastStore } = await import("@/stores/toast");
     useToastStore().show("Failed to convert note", "error");
@@ -146,7 +112,7 @@ async function convertToTask() {
           Edit
         </router-link>
         <button
-          v-if="!hasCompanionTask"
+          v-if="!store.currentNote.is_task"
           class="btn-convert"
           @click="convertToTask"
           :disabled="converting"
@@ -175,22 +141,6 @@ async function convertToTask() {
         @click="onBodyClick"
       ></div>
 
-      <div v-if="linkedTasks.length" class="linked-tasks">
-        <h2>Companion Task</h2>
-        <ul class="linked-tasks-list">
-          <li v-for="task in linkedTasks" :key="task.id" class="linked-task-item">
-            <StatusBadge
-              :status="task.status"
-              clickable
-              @click="toggleTaskStatus(task)"
-            />
-            <router-link :to="`/tasks/${task.id}`" class="linked-task-link">
-              {{ task.title || "Untitled" }}
-            </router-link>
-          </li>
-        </ul>
-      </div>
-
       <div v-if="backlinks.length" class="backlinks">
         <h2>Backlinks</h2>
         <ul class="backlinks-list">
@@ -256,18 +206,15 @@ async function convertToTask() {
   margin-bottom: 1rem;
   flex-wrap: wrap;
 }
-.linked-tasks,
 .backlinks {
   margin-top: 2rem;
   border-top: 1px solid var(--color-border);
   padding-top: 1rem;
 }
-.linked-tasks h2,
 .backlinks h2 {
   font-size: 1.1rem;
   margin: 0 0 0.75rem;
 }
-.linked-tasks-list,
 .backlinks-list {
   list-style: none;
   margin: 0;
@@ -276,19 +223,16 @@ async function convertToTask() {
   flex-direction: column;
   gap: 0.5rem;
 }
-.linked-task-item,
 .backlink-item {
   display: flex;
   align-items: center;
   gap: 0.5rem;
 }
-.linked-task-link,
 .backlink-link {
   color: var(--color-text);
   text-decoration: none;
   font-size: 0.95rem;
 }
-.linked-task-link:hover,
 .backlink-link:hover {
   color: var(--color-primary);
 }