fix(dashboard): month chart shows Sem 1-4 of current month

- Month view now groups by weeks of the current calendar month
- Labels are Sem 1, Sem 2, Sem 3, Sem 4
- Historical sales grouped by day-of-month into the 4 week buckets
- Bump dashboard.js to ?v=7

pos/templates/dashboard.html

@@ -568,7 +568,7 @@
   <script src="/pos/static/js/pos-utils.js?v=2" defer></script>
   <script src="/pos/static/js/sidebar.js" defer></script>
   <script src="/pos/static/js/dashboard-stats.js?v=3" defer></script>
-  <script src="/pos/static/js/dashboard.js?v=6" defer></script>
+  <script src="/pos/static/js/dashboard.js?v=7" defer></script>
   <script src="/pos/static/js/sync-engine.js" defer></script>
   <script>if('serviceWorker' in navigator){navigator.serviceWorker.register('/pos/sw.js',{scope:'/pos/'});}</script>
   <script src="/pos/static/js/pwa-install.js" defer></script>