Loki Mode

Fix: /api/tasks no longer 500s on a malformed dashboard-state.json

• The task board never blanks out on a bad state file. dashboard-state.json
  is user/agent-written and can be malformed or partially written. If its
  tasks value was not a dict, or a task group was not a list, or a group item
  was not a dict, GET /api/tasks raised an AttributeError (from
  task_groups.get / task.get) that the surrounding (JSONDecodeError, KeyError) handler did not catch, 500ing the request and blanking the whole
  board. The state-group reader now coerces defensively: a non-dict tasks is
  treated as empty, a non-list group is skipped, and a non-dict item is skipped,
  so a bad shape degrades to "skip that part" instead of a crash. The valid
  tasks still render. (The queue-file reader already had these guards; this
  closes the one remaining gap, found during the v7.104.3 task-list review.)

• Regression coverage: tests/dashboard/test_tasks_malformed_state.py (dict-not-
  list group, non-dict tasks, non-dict item), each proven to 500 on the old
  code and pass on the fix.