feat: reskin admin pages to zine design system

Migrate the entire admin section from the dark guild-* Tailwind theme
to the zine design system (dashed borders, CSS custom properties,
Brygada 1918 + Commit Mono, cream/dark mode palette).

- Replace admin top-nav layout with sidebar matching default layout
- Reskin dashboard, members, events, series management pages
- Reskin events/create and series/create form pages
- Add dev-only test login endpoint (GET /api/dev/test-login)
- Redirect duplicate admin/dashboard.vue to /admin
- Update CLAUDE.md design system docs

CLAUDE.md

@@ -14,6 +14,8 @@ npm run build      # Production build
 npm run preview    # Preview production build
 ```
 
+**Dev helpers:** `GET /api/dev/test-login` — creates a test admin user and sets auth cookie (dev only, blocked in production). Navigate to this URL to access admin pages during development.
+
 No test framework is currently configured.
 
 ## Architecture
@@ -35,8 +37,8 @@ No test framework is currently configured.
 - `app/composables/` — State management via `useState()` (no Pinia/Vuex). Key composables: `useAuth`, `useHelcim`, `useMemberPayment`, `useMemberStatus`
 - `app/config/` — Circle definitions (`circles.js`) and contribution tiers (`contributions.js`) used across frontend and forms
 - `app/middleware/` — Route guards: `auth.js` (member pages), `admin.js` (admin pages), `coming-soon.global.js` (launch gate)
-- `app/layouts/` — `default`, `admin`, `landing`, `coming-soon`
-- `server/api/` — Nitro API routes organized by feature: `auth/`, `events/`, `members/`, `helcim/`, `series/`, `updates/`, `admin/`, `slack/`
+- `app/layouts/` — `default` (sidebar, member/public), `admin` (sidebar, admin pages), `landing`, `coming-soon`
+- `server/api/` — Nitro API routes organized by feature: `auth/`, `events/`, `members/`, `helcim/`, `series/`, `updates/`, `admin/`, `slack/`, `dev/` (dev-only helpers)
 - `server/models/` — Mongoose schemas: `Member`, `Event`, `Series`, `Update`
 - `server/utils/` — Service integrations: `mongoose.js`, `helcim.js`, `resend.js`, `slack.ts`, `tickets.js`
 
@@ -48,14 +50,15 @@ Member statuses: `pending_payment`, `active`, `suspended`, `cancelled`.
 
 Events support ticketing with circle-specific pricing overrides and can be grouped into Series with bundled passes.
 
-### Design System
+### Design System (Zine Direction)
 
-- **Colors:** `guild-*` (warm neutral), `candlelight-*` (amber/gold accent), `parchment-*` (cream surfaces), `ember-*` (rust accent), `earth-*` (brown/ochre) — defined in `app/assets/css/main.css`
-- **Circle tokens:** `--color-circle-community`, `--color-circle-founder`, `--color-circle-practitioner` with `-light`, `-dark`, `-bg` variants
-- **Typography:** Inter (body), Quietism (display/headers, self-hosted from `public/fonts/`), Ubuntu Mono (code)
-- **Theme:** `primary: amber`, `neutral: stone` — configured in `app/app.config.ts`
-- **Effects:** `.candlelight-glow`, `.warm-text`, `.ink-grain`, `.paper-texture`, `.woodcut-border`, `.guild-stamp`, `.halftone-texture`, `.dithered-bg`, `.dithered-warm`
-- **Content:** `.prose-guild` class for wiki/long-form content with warm palette and Quietism headings
+- **Palette:** CSS custom properties in `:root` / `.dark` blocks in `app/assets/css/main.css` — `--bg` (cream/#f4efe4), `--surface`, `--border`, `--candle` (gold accent), `--ember` (rust accent), `--text`, `--text-bright`, `--text-dim`, `--text-faint`, `--parch` (inverted blocks), `--c-community`, `--c-founder`, `--c-practitioner`
+- **Typography:** Brygada 1918 (serif, display/headings) + Commit Mono (monospace, body/UI/everything structural) — loaded via Google Fonts in `nuxt.config.ts`
+- **Theme:** `primary: amber`, `neutral: stone` — configured in `app/app.config.ts`. Tailwind `@theme` maps `--font-sans` and `--font-mono` to Commit Mono, `--font-display` to Brygada 1918
+- **Key classes:** `.btn` / `.btn-primary` / `.btn-danger` (buttons), `.field` (form groups), `.badge` (circle badges), `.section-label` (10px uppercase headers), `.dashed-box` (bordered containers), `.section-divider`
+- **Visual language:** Dashed borders (1px dashed), cream backgrounds, no rounded corners, text-forward density, minimal decoration
+- **Color mode:** `@nuxtjs/color-mode` with preference `system`, fallback `light`. Dark mode via `.dark` class on `<html>`
+- **Layouts:** `default` (sidebar + main, member/public pages), `admin` (sidebar + main, admin pages), `landing` (horizontal nav, unused)
 
 ### Environment