feat(tasks): POST /api/tasks/:id/consolidate + separate body/description fields

New endpoint manually triggers a consolidation pass for a single task.
Bypasses the auto_consolidate_tasks setting since the user is asking
explicitly. Returns the task with the freshly-written body and
consolidated_at timestamp.

Also un-aliases description and body in the create/update task routes
(was: description folded into body as legacy fallback). With separate
fields under the task-as-durable-record design, both flow through as
distinct kwargs to create_note / update_note.

src/fabledassistant/routes/tasks.py

@@ -89,7 +89,11 @@ async def list_tasks_route():
 async def create_task_route():
     uid = get_current_user_id()
     data = await request.get_json()
-    body = data.get("body", "") or data.get("description", "")
+    # Description (user-stated goal) and body (machine-maintained summary) are
+    # separate fields under the task-as-durable-record design. Don't fold one
+    # into the other.
+    body = data.get("body", "")
+    description = data.get("description")
     tags = data.get("tags", [])
 
     due_date = parse_iso_date(data.get("due_date"), "due_date")
@@ -120,6 +124,7 @@ async def create_task_route():
         uid,
         title=data.get("title", ""),
         body=body,
+        description=description,
         status=status,
         priority=priority,
         due_date=due_date,
@@ -178,11 +183,12 @@ async def update_task_route(task_id: int):
         except ValueError:
             return jsonify({"error": f"Invalid priority: {data['priority']}"}), 400
 
-    # Accept both "body" and "description" (prefer body)
+    # Body and description are distinct fields under the task-as-durable-record
+    # design. Don't alias one to the other.
     if "body" in data:
         fields["body"] = data["body"]
-    elif "description" in data:
-        fields["body"] = data["description"]
+    if "description" in data:
+        fields["description"] = data["description"]
 
     if "due_date" in data:
         if data["due_date"]:
@@ -276,3 +282,25 @@ async def delete_task_route(task_id: int):
     if not deleted:
         return not_found("Task")
     return "", 204
+
+
+@tasks_bp.route("/<int:task_id>/consolidate", methods=["POST"])
+@login_required
+async def consolidate_task_route(task_id: int):
+    """Manually trigger a consolidation pass for a task.
+
+    Bypasses the auto_consolidate_tasks setting (the user is asking
+    explicitly). Returns the task's updated state including the freshly-
+    written body and consolidated_at timestamp.
+    """
+    uid = get_current_user_id()
+    if not await can_write_note(uid, task_id):
+        return jsonify({"error": "Permission denied"}), 403
+
+    from fabledassistant.services.consolidation import consolidate_task
+    await consolidate_task(uid, task_id)
+
+    note = await get_note(uid, task_id)
+    if note is None:
+        return not_found("Task")
+    return jsonify(note.to_dict())