templates, handlers, CSS, JS: special cakes UI, HTMX nav, dashboard overhaul

Special cakes UI: overlay drawer, basket integration, catalogue tag
filter, form parsing, JS save/edit/remove.
HTMX navigation: MainContent component, nav links with hx-get,
handlers return partial on HX-Request.
Dashboard: metrics grid, CakeBreakdown, OrderRow with status select,
CakeCounts/OrderCounts, torty filter, tort badge, results-pane.
Collapsible sidebar: toggle button, localStorage, CSS transitions.
Location field: dropdown replaced with pill toggle.
Inline style cleanup: moved to CSS classes (tag-grid, grow, icon.sm,
header-actions, toggle-group, success-icon, etc.).
Dead CSS removal: pagination, status-chip, badge-pill, login-page.
Helpers: exported CakeTitle/OrderTitle, added tagNames, tagIDsComma,
orderItemsDesc, specialCakeDetail, removed unused helpers.

server/static/basket.css

@@ -42,6 +42,10 @@
             white-space: nowrap;
         }
 
+        .basket-actions .action-btn .material-symbols-outlined {
+            font-size: 1rem;
+        }
+
         .remove {
             color: var(--error);
             cursor: pointer;