v1.3.1 — 点击时的旋转反馈

Fix: a click refresh was silent once the first reading had arrived.

The shared store flipped to loading only before the first reading, so
afterwards a manual refresh changed nothing visually. Now the store keeps
a separate refreshing flag:

• previous reading stays on screen (no blinking numbers)
• the gauge spins, the label dims to 50%, cursor becomes progress
• data-state="loading" + aria-busy="true" while in flight

Click still forces a fresh read (?refresh=1, bypassing the Host reuse
window); polling keeps using the reuse window.