Add live projected HF preview beside leverage slider

[Sikkra]

Summary

• add a dedicated projected-HF badge directly under the leverage slider
• update the badge on every leverage preview refresh using the same min-HF thresholds that gate transactions
• show safe / warning / danger styling and mobile wrapping for the live HF status

Verification

• npm run build
• git diff --check
• Browser check on http://127.0.0.1:5201/: demo mode showed Projected HF 1.600 at 2.0x, then after changing leverage to 4.8x updated live to 1.011 with the warning state; current-page console logs were clean

Closes #3