feat: design system v2 with liquid glass aesthetic

Overhaul design constants for OLED-first dark mode:
- Colors: brand palette, phase colors, glass/shadow tokens, gradients
- Typography: Inter font scale matching iOS type system
- Spacing: 4px base unit with layout constants
- Border radius: liquid glass card radii
- Animations: spring/timing presets for UI transitions

Add v2 product docs (PRD, PDD, BDSD) and update CLAUDE.md.
Install expo-video, expo-sharing, @expo-google-fonts/inter.

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

package.json

@@ -5,12 +5,14 @@
   "scripts": {
     "start": "expo start",
     "reset-project": "node ./scripts/reset-project.js",
-    "android": "expo start --android",
-    "ios": "expo start --ios",
+    "android": "expo run:android",
+    "ios": "expo run:ios",
     "web": "expo start --web",
     "lint": "expo lint"
   },
   "dependencies": {
+    "@expo-google-fonts/inter": "^0.4.2",
+    "@expo/ui": "~0.2.0-beta.9",
     "@expo/vector-icons": "^15.0.3",
     "@react-native-async-storage/async-storage": "^2.2.0",
     "@react-navigation/bottom-tabs": "^7.4.0",
@@ -27,10 +29,12 @@
     "expo-linear-gradient": "~15.0.8",
     "expo-linking": "~8.0.11",
     "expo-router": "~6.0.23",
+    "expo-sharing": "~14.0.8",
     "expo-splash-screen": "~31.0.13",
     "expo-status-bar": "~3.0.9",
     "expo-symbols": "~1.0.8",
     "expo-system-ui": "~6.0.9",
+    "expo-video": "~3.0.16",
     "expo-web-browser": "~15.0.10",
     "react": "19.1.0",
     "react-dom": "19.1.0",