Add Android support with configurable server URL and location permissions

- Add shared_preferences for persisting server URL
- Add SettingsService and PlatformService
- Add server URL input field on non-web platforms
- Make ApiConfig baseUrl configurable at runtime
- Add Android location permissions (ACCESS_FINE/COURSE_LOCATION, INTERNET)
- Request location permission on login and map init
- Fix geo_id type: use String instead of int (UUID format)
- Align share_service with API spec: remove unique_id, use share_id only
- Fix watch endpoint response: last_update instead of created_at
- Add error handling with SnackBars for geo operations
- Wrap login screen in SingleChildScrollView for keyboard handling
- Update map tile layer with userAgentPackageName for OSM

web/swagger/swagger-initializer.js

@@ -0,0 +1,19 @@
+window.onload = function() {
+  //<editor-fold desc="Changeable Configuration Block">
+
+  // the following lines will be replaced by docker/configurator, when it runs in a docker-container
+  window.ui = SwaggerUIBundle({
+    url: "/swagger/swagger.yaml",
+    dom_id: '#swagger-ui',
+    deepLinking: false,
+    presets: [
+      SwaggerUIBundle.presets.apis
+    ],
+    plugins: [
+      SwaggerUIBundle.plugins.DownloadUrl
+    ],
+    layout: "BaseLayout"
+  });
+
+  //</editor-fold>
+};