mobile: fix notebook icons + redesign home/notebooks + inline MD parser in WebView

- notebooks.tsx: detect Lucide icon names (folder, book, etc.) vs emoji
  -> render <Folder> component instead of raw string 'folder'
  -> colored icon wrap using notebook color
- home.tsx: full redesign — header greeting + quick actions + recent list
  -> section-based layout, dense note rows with chevron
- note/[id].tsx: remove 'marked' import (Metro bundler issue)
  -> inline minimal MD→HTML parser runs inside WebView JS context
  -> handles headings, lists, blockquotes, code blocks, inline styles
  -> zero external dependency, works 100% offline
- package.json: remove 'marked' dependency

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

memento-mobile/package.json

@@ -20,7 +20,6 @@
     "expo-splash-screen": "~31.0.13",
     "expo-status-bar": "~3.0.9",
     "lucide-react-native": "^0.477.0",
-    "marked": "^18.0.4",
     "react": "19.1.0",
     "react-native": "0.81.5",
     "react-native-safe-area-context": "~5.6.0",