feat: initial HELIX scaffold — R&D showcase platform

SvelteKit 2 + Svelte 5 + TypeScript site. SQLite via Drizzle. Gitea OAuth
for authoring (RnD org-gated). Pure SVG + CSS DNA helix on landing.

What lands
- Landing hero with animated two-strand SVG helix + tagline
- /projects + /projects/[slug] (markdown body, dashboard embed allowlist)
- /posts + /posts/[slug]
- Auth-gated /projects/new + /posts/new forms
- Gitea OAuth flow (state, code exchange, org-membership check, sessions)
- Sliding-window cookie sessions (SHA-256 hashed token storage)
- Dockerfile + docker-compose with named-volume SQLite
- Idempotent seed (EVOLV + HELIX projects, welcome post)

Stack notes
- Tailwind v3 (Node 18 compat; v4 needs Node 20+)
- drizzle-orm 0.45+ (patched, no SQL-identifier escape vuln)
- marked for markdown; iframe embeds gated by DASHBOARD_ALLOWED_HOSTS

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tailwind.config.js

@@ -0,0 +1,31 @@
+/** @type {import('tailwindcss').Config} */
+export default {
+  content: ['./src/**/*.{html,js,svelte,ts}'],
+  theme: {
+    extend: {
+      colors: {
+        helix: {
+          area: '#0f52a5',
+          process: '#0c99d9',
+          unit: '#50a8d9',
+          equipment: '#86bbdd',
+          control: '#a9daee',
+          bg: '#07111d',
+          'bg-2': '#0c1c30',
+          'bg-3': '#122842',
+          border: '#1f3a5e',
+          ink: '#e6f1fb',
+          'ink-dim': '#8fa6b8',
+          'ink-faint': '#5b7388',
+          accent: '#4dd0c2',
+          'accent-2': '#c084fc'
+        }
+      },
+      fontFamily: {
+        sans: ['Inter', 'system-ui', '-apple-system', 'Segoe UI', 'sans-serif'],
+        mono: ['JetBrains Mono', 'ui-monospace', 'SFMono-Regular', 'monospace']
+      }
+    }
+  },
+  plugins: []
+};