Add point-in-time stock membership lookup to the sector radar module
(GET /sector-radar/stocks/{ts_code}/membership) reading the existing
dc_index/dc_member snapshots, and surface industries plus concept chips
in the selection signal detail panel with graceful no-data hiding.
Add an optional brick_chart series to the selection chart API, computed
from the shared gold-brick formula when strategy=gold_brick, and render
a fourth grid with red/green brick bars between the volume and J grids.
yuxuanhui