feat: brain-engine + brain-ui + docs — template full stack standalone

- brain-engine: server, embed, search, RAG, MCP, start.sh (standalone)
- brain-ui: source React complète, build.sh, DocsView avec tier colors
- docs: 14 pages guides humains (getting-started, architecture, sessions, workflows, agents, vues tier)
- brain-compose.yml v0.9.0: tier featured ajouté, sessions/agents par tier, coach_level, API key schema
- DISTRIBUTION_CHECKLIST v1.2: brain-engine + brain-ui + docs dans la checklist

brain-ui/vite.config.ts

@@ -0,0 +1,19 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+
+export default defineConfig({
+  plugins: [react()],
+  base: '/ui/',
+  server: {
+    port: 5173,
+    proxy: {
+      '/api': {
+        target: 'http://localhost:7700',
+        changeOrigin: true,
+        secure: false,
+        ws: true,
+        rewrite: (path: string) => path.replace(/^\/api/, ''),
+      },
+    },
+  },
+})