fix: frontend UX improvements (SSE status, responsive tables, dark mode, login toggle, theme)

- Add SSE connection status banner showing when real-time updates are lost (UX-H8, UX-M1)
- Add password visibility toggle on login page (UX-H10)
- Add dark mode variants to stat card backgrounds (UX-M11)
- Add overflow-x-auto to tables for mobile responsiveness (UX-H9)
- Add flex-wrap to stage header for mobile overflow (UX-H11)
- Fix theme store system preference listener reactivity (UX-M12)
- Parallelize registry health checks (UX-L4)

web/src/routes/projects/+page.svelte

@@ -220,7 +220,7 @@
 			icon="projects"
 		/>
 	{:else}
-		<div class="overflow-hidden rounded-xl border border-[var(--border-primary)] bg-[var(--surface-card)] shadow-[var(--shadow-sm)]">
+		<div class="overflow-x-auto rounded-xl border border-[var(--border-primary)] bg-[var(--surface-card)] shadow-[var(--shadow-sm)]">
 			<table class="min-w-full divide-y divide-[var(--border-primary)]">
 				<thead class="bg-[var(--surface-card-hover)]">
 					<tr>