feat(design): apply Monolith Editorial design system to all Fase 1 screens

- Remove all 1px border separators (sidebar border-r, page header border-b,
  section border-t, member list divide-y, invite card border). Separation is
  now achieved via background color shifts and whitespace per the "No-Line" rule.
- Fix sidebar: bg-surface-raised vs bg-background creates tonal separation.
- Correct dark background to #020617 (slate-950) per spec.
- Add surface-container-low, text-primary/secondary/muted, destructive tokens.
- Fix CSS variable color space: all tokens are RGB triplets; switch Tailwind
  config and app.css from hsl() to rgb() to prevent yellow/warm color bleed.
- Replace emoji nav icons with Lucide icons at 16px / 1.5 stroke-width.
- Apply Masthead typography (uppercase Label-MD + Title-LG) to all page headers
  and section labels across lists, tasks, notes, search, settings, manage.
- Destructive action (sign out) uses bg-destructive per spec.
- Add `just serve` command: builds and runs the prod Node server at :3000
  against the dev Docker stack for production build testing.
- Add nav_collective i18n key (en + es).

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

apps/web/src/routes/(app)/search/+page.svelte

@@ -3,10 +3,15 @@
 </script>
 
 <div class="flex flex-1 flex-col overflow-hidden">
-	<header class="flex h-14 items-center border-b border-slate-200 px-6 dark:border-slate-700">
-		<h1 class="text-base font-semibold text-slate-900 dark:text-slate-50">{m.search_title()}</h1>
+	<header class="px-8 pb-4 pt-8">
+		<p class="mb-1 text-[13px] font-semibold uppercase tracking-[0.05em] text-text-secondary">
+			{m.nav_search()}
+		</p>
+		<h1 class="text-[20px] font-semibold tracking-[-0.01em] text-slate-900 dark:text-slate-50">
+			{m.search_title()}
+		</h1>
 	</header>
-	<div class="flex-1 overflow-y-auto p-6">
+	<div class="flex-1 overflow-y-auto px-8 py-6">
 		<!-- Fase 4: search content -->
 	</div>
 </div>