Add manual scheduled task entry

Lets users log tasks the Linux agent can't discover on its own (e.g.
Docker-based backup jobs) directly in the UI. Tasks now carry an
origin ('agent' | 'manual') so the agent's report-sync logic only
ever creates/updates/stale-marks agent-sourced rows, leaving manual
entries untouched; the API rejects edits/deletes of agent-sourced
tasks to keep that boundary enforced server-side too.

web/src/components/TaskTable.tsx

@@ -13,7 +13,13 @@ function describeSchedule(task: TaskRecord): string {
   return task.scheduleExpression;
 }
 
-export default function TaskTable({ tasks }: { tasks: TaskRecord[] }) {
+interface Props {
+  tasks: TaskRecord[];
+  onEdit?: (task: TaskRecord) => void;
+  onDelete?: (task: TaskRecord) => void;
+}
+
+export default function TaskTable({ tasks, onEdit, onDelete }: Props) {
   return (
     <table className="task-table">
       <thead>
@@ -23,6 +29,7 @@ export default function TaskTable({ tasks }: { tasks: TaskRecord[] }) {
           <th>Schedule</th>
           <th>Next run</th>
           <th>Status</th>
+          <th></th>
         </tr>
       </thead>
       <tbody>
@@ -43,6 +50,19 @@ export default function TaskTable({ tasks }: { tasks: TaskRecord[] }) {
               ) : (
                 <span className="badge badge-disabled">Disabled</span>
               )}
+              {task.origin === "manual" && <span className="badge badge-manual">Manual</span>}
+            </td>
+            <td className="actions">
+              {task.origin === "manual" && (
+                <>
+                  <button className="btn btn-small" onClick={() => onEdit?.(task)}>
+                    Edit
+                  </button>
+                  <button className="btn btn-small btn-danger" onClick={() => onDelete?.(task)}>
+                    Delete
+                  </button>
+                </>
+              )}
             </td>
           </tr>
         ))}