Introduce `demo_data` management command for populating or removing demo fixtures in the system, facilitating testing and demonstration. Enhancements include low stock product list UI with product images and integration of value formatting for financial KPIs.
Fixes: 1) Remove redundant breaks and unnecessary div wrappings; 2) Simplify filters component by eliminating unnecessary card wrapper;
Extra: Refactor and clean up admin dashboard templates for decluttered structure and improved code consistency;
Fixes: None;
Extra: 1) Remove redundant comments from `_kpis.html`; 2) Exclude unused `_income_overview.html` include from `index.html`; 3) Comment out GA/Yandex/Ads integration placeholder in `_filters.html`.
Fixes: 1) Replace failed daily stats with empty lists instead of crashing; 2) Fix inconsistent variable scoping and cleanup;
Extra: 1) Refactor daily stats logic to handle exceptions gracefully; 2) Improve readability by grouping related metrics; 3) Add type annotations for new context variables.
