Add cxyz Android project structure and initial configuration

- Introduced a new Flutter project for the cxyz Android manga/comic reader, including essential files such as pubspec.yaml, AndroidManifest.xml, and Gradle configuration.
- Added .gitignore files to exclude unnecessary files and directories for both the main project and Android-specific files.
- Implemented initial README.md with project description, features, setup instructions, and API details for ComicLand, MangaRead, and MangaTown.
- Configured analysis options and dependencies in pubspec.yaml to support Flutter development.
- Established a pnpm workspace and lockfile for dependency management.
- Included various Android resources such as icons, styles, and launch backgrounds for a complete application setup.

cxyz-android/lib/sources/mangatown/constants.dart

@@ -0,0 +1,24 @@
+/// MangaTown mobile (`m.mangatown.com`) constants.
+library;
+
+const mangaTownOrigin = 'https://m.mangatown.com';
+
+const mangaTownMobileUa =
+    'Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 '
+    '(KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1';
+
+const mangaTownHtmlHeaders = <String, String>{
+  'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
+  'Accept-Language': 'en-US,en;q=0.9',
+  'User-Agent': mangaTownMobileUa,
+};
+
+const mangaTownImageHeaders = <String, String>{
+  'Accept': 'image/avif,image/webp,image/apng,image/*,*/*;q=0.8',
+  'Accept-Language': 'en-US,en;q=0.9',
+  'Referer': '$mangaTownOrigin/',
+  'User-Agent': mangaTownMobileUa,
+};
+
+/// Site catalog page size (Latest / Hot / Directory).
+const mangaTownCatalogPageSize = 20;