feat(pos): add shop and statistics modules with components, services, and routing

- Implemented shop module with root component, loading state, and invoice handling.
- Created statistics module with invoice type card component, API routes, and data models.
- Added season picker component for selecting year and season.
- Integrated services for fetching statistics data and managing state.
- Established routing for statistics and shop views.

angular.json

@@ -209,6 +209,8 @@
                             ".webp": "file"
                         },
                         "styles": [
+                            "node_modules/flatpickr-wrap/dist/flatpickr.css",
+                            "node_modules/flatpickr-wrap/dist/themes/confetti.css",
                             "src/assets/styles.scss"
                         ],
                         "tsConfig": "tsconfig.app.json"
@@ -250,6 +252,8 @@
                         "inlineStyleLanguage": "scss",
                         "karmaConfig": "karma.conf.js",
                         "styles": [
+                            "node_modules/flatpickr-wrap/dist/flatpickr.css",
+                            "node_modules/flatpickr-wrap/dist/themes/confetti.css",
                             "src/assets/styles.scss"
                         ],
                         "tsConfig": "tsconfig.spec.json"