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>

CLAUDE.md

@@ -93,6 +93,7 @@ infra/
 ```bash
 just setup            # first-time (and idempotent) local environment setup
 just dev              # start docker-compose.dev.yml + SvelteKit dev server
+just serve            # build + start prod Node server at :3000 against dev Docker stack
 just stop             # stop all services (Docker stack + Vite dev server)
 just dev-stop         # stop Docker stack only
 just dev-clean        # stop Docker stack and remove all volumes (full reset)
@@ -173,7 +174,9 @@ Logout is a single call — `supabase.auth.signOut()` — which clears the GoTru
 
 7. **`onAuthStateChange` fires `INITIAL_SESSION` on page load, not `SIGNED_IN`.** `SIGNED_IN` only fires immediately after a login flow. Load collective data whenever the session is present, regardless of event type — otherwise collectives are never loaded on page refresh. Pattern in root `+layout.svelte`: `if (session) { await loadUserCollectives(...) }` covering `INITIAL_SESSION`, `SIGNED_IN`, and `TOKEN_REFRESHED`.
 
-8. **PWA service worker: do not use `injectManifest` with a file named `service-worker.ts`.** SvelteKit intercepts any file at `src/service-worker.[jt]s` and enforces a hard restriction: only `$service-worker` and `$env/static/public` may be imported — Workbox modules are blocked. With `injectManifest`, `@vite-pwa/sveltekit` tries to find the compiled SW output at `.svelte-kit/output/client/service-worker.js`, but SvelteKit never produces it (compilation fails on the blocked imports). Fix for Fase 1–2a: use `generateSW` strategy (plugin auto-generates the SW, no custom source needed). Fix for Fase 2b when a custom SW is needed: name the file `src/sw.ts` — SvelteKit does not recognise it as a service worker — and set `strategies: 'injectManifest'`, `filename: 'sw.ts'` in `vite.config.ts`.
+9. **CSS custom properties use RGB triplets — always use `rgb()`, never `hsl()`.** All design tokens in `app.css` store values as space-separated RGB triplets (e.g. `51 65 85`). Using `hsl(var(--token))` interprets the first value as a hue degree — `hsl(51 65% 85%)` renders as light yellow, not slate-700. The Tailwind config and any `background-color`/`color` declarations in `app.css` must use `rgb(var(--token) / <alpha>)`.
+
+10. **PWA service worker: do not use `injectManifest` with a file named `service-worker.ts`.** SvelteKit intercepts any file at `src/service-worker.[jt]s` and enforces a hard restriction: only `$service-worker` and `$env/static/public` may be imported — Workbox modules are blocked. With `injectManifest`, `@vite-pwa/sveltekit` tries to find the compiled SW output at `.svelte-kit/output/client/service-worker.js`, but SvelteKit never produces it (compilation fails on the blocked imports). Fix for Fase 1–2a: use `generateSW` strategy (plugin auto-generates the SW, no custom source needed). Fix for Fase 2b when a custom SW is needed: name the file `src/sw.ts` — SvelteKit does not recognise it as a service worker — and set `strategies: 'injectManifest'`, `filename: 'sw.ts'` in `vite.config.ts`.
 
 ## Sync Strategy