feat: design system overhaul — sidebar, AI chats, settings, brainstorm, color cleanup

- Sidebar: dynamic brand-accent colors, brainstorm section restyled
- AI chat general: popup panel with expand/collapse, hides when contextual AI open
- AI chat contextual: tabs reordered (Actions first), X close button, height fix
- Settings: all tabs restyled, 6 new color presets (sage, terracotta, iron, etc.)
- Global color cleanup: emerald/orange hardcoded → brand-accent dynamic
- Brainstorm page: orange → brand-accent throughout
- PageEntry animation component added to key pages
- Floating AI button: bg-brand-accent instead of hardcoded black
- i18n: all 15 locales updated with new AI/billing keys
- Billing: freemium quota tracking, BYOK, stripe subscription scaffolding
- Admin: integrated into new design
- AGENTS.md + CLAUDE.md project rules added

architectural-grid_landing/vite.config.ts

@@ -0,0 +1,24 @@
+import tailwindcss from '@tailwindcss/vite';
+import react from '@vitejs/plugin-react';
+import path from 'path';
+import {defineConfig, loadEnv} from 'vite';
+
+export default defineConfig(({mode}) => {
+  const env = loadEnv(mode, '.', '');
+  return {
+    plugins: [react(), tailwindcss()],
+    define: {
+      'process.env.GEMINI_API_KEY': JSON.stringify(env.GEMINI_API_KEY),
+    },
+    resolve: {
+      alias: {
+        '@': path.resolve(__dirname, '.'),
+      },
+    },
+    server: {
+      // HMR is disabled in AI Studio via DISABLE_HMR env var.
+      // Do not modify—file watching is disabled to prevent flickering during agent edits.
+      hmr: process.env.DISABLE_HMR !== 'true',
+    },
+  };
+});