feat: add Swagger UI docs, custom CORS middleware, and request logging

- Add Swagger UI files and updated API spec for Family Safety Tracker
- Replace shelf_cors_headers with custom CORS middleware in server.dart
- Add request_logger middleware with timing for auth and geo routes
- Add REGISTRATION_SECRET_KEY to .env for registration validation
- Remove postgres port exposure from docker-compose.yml
- Update opencode.json model configuration
- Add crypto dependency and update Flutter web assets

web/swagger/index.css

@@ -0,0 +1,16 @@
+html {
+    box-sizing: border-box;
+    overflow: -moz-scrollbars-vertical;
+    overflow-y: scroll;
+}
+
+*,
+*:before,
+*:after {
+    box-sizing: inherit;
+}
+
+body {
+    margin: 0;
+    background: #fafafa;
+}