fix(web): fix UI bugs and unify design tokens

- Add missing .nofx-glass CSS class (used in 20+ places but undefined)
- Fix Input component referencing undefined --brand-black/--brand-light-gray
- Unify background colors to #0B0E11 (was 3 different near-blacks)
- Switch body font from IBM Plex Mono to Inter for readability
- Improve chat bubble contrast (bg 0.03→0.05, border 0.05→0.08)
- Brighten timestamp (#2c2c42→#5a5a72) and disclaimer (#1e1e32→#4a4a62)
- Unify ::selection color to gold (was orange)
- Remove global button:hover translateY that conflicted with active:scale

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/tailwind.config.js

@@ -14,8 +14,8 @@ export default {
           highlight: '#FFD700',
         },
         'nofx-bg': {
-          DEFAULT: '#05070A', // Deep Void
-          deeper: '#020304',  // Abyssal
+          DEFAULT: '#0B0E11', // Deep Void
+          deeper: '#050709',  // Abyssal
           lighter: '#0E1217', // Surface
         },
         'nofx-accent': '#00F0FF', // Cyan Cyber