refactor: extract reusable library

- move reusable domain, data, state, ui code into src/lib
- update host screens to consume new library exports
- document architecture and configure path aliases
- bump astro integration dependencies for compatibility

Refs #30

tsconfig.json

@@ -10,6 +10,11 @@
   "compilerOptions": {
     "jsx": "react-jsx",
     "jsxImportSource": "preact",
-    "lib": ["ES2020", "DOM", "DOM.Iterable"]
+    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["src/*"],
+      "@lib/*": ["src/lib/*"]
+    }
   }
 }