Fix Tezos ꜩ symbol not rendering on mobile Safari
Force-load the ꜩ glyph from Noto Sans Mono via Google Fonts text parameter,
bypassing unicode-range subsetting that mobile Safari fails to trigger.
Also add Noto Sans Mono fallback to buy.html wallet button font stack.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>