Comprehensive UX polish: fix 19 friction points across all pages

Addresses broken interactions (notification bell, browser dialogs),
missing feedback states (disabled buttons, pricing changes, paused
indicator), unclear affordances (research queue, model tuning, funding
requirements), and navigation gaps (hash routing, keyboard shortcuts,
clickable dashboard cards, sidebar grouping, tutorial hints).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/components/layout/Sidebar.tsx

@@ -70,22 +70,25 @@ export function Sidebar() {
 
           const isActive = activePage === page;
           const isNew = newPages.has(page);
+          const showDivider = page === 'talent' || page === 'achievements';
           return (
-            <button
-              key={page}
-              onClick={() => handleNavClick(page)}
-              className={`w-full flex items-center gap-3 px-4 py-2.5 text-sm transition-colors ${
-                isActive
-                  ? 'bg-accent/10 text-accent-light border-r-2 border-accent'
-                  : 'text-surface-300 hover:bg-surface-800 hover:text-surface-100'
-              }`}
-            >
-              <Icon size={18} />
-              {label}
-              {isNew && (
-                <span className="ml-auto text-[10px] font-bold bg-accent text-white px-1.5 py-0.5 rounded">NEW</span>
-              )}
-            </button>
+            <div key={page}>
+              {showDivider && <div className="border-t border-surface-700 my-1 mx-4" />}
+              <button
+                onClick={() => handleNavClick(page)}
+                className={`w-full flex items-center gap-3 px-4 py-2.5 text-sm transition-colors ${
+                  isActive
+                    ? 'bg-accent/10 text-accent-light border-r-2 border-accent'
+                    : 'text-surface-300 hover:bg-surface-800 hover:text-surface-100'
+                }`}
+              >
+                <Icon size={18} />
+                {label}
+                {isNew && (
+                  <span className="ml-auto text-[10px] font-bold bg-accent text-white px-1.5 py-0.5 rounded">NEW</span>
+                )}
+              </button>
+            </div>
           );
         })}
       </nav>