Initial commit: SejeteralO water tarification platform

Full-stack app for participatory water pricing using Bezier curves.
- Backend: FastAPI + SQLAlchemy + SQLite with JWT auth
- Frontend: Nuxt 4 + TypeScript with interactive SVG editor
- Math engine: cubic Bezier tarification with Cardano solver
- Admin: commune management, household import, vote monitoring, CMS
- Citizen: interactive curve editor, vote submission
- Docker-compose deployment ready

Includes fixes for:
- Impact table snake_case/camelCase property mismatch
- CMS content backend API + frontend editor (was stub)
- Admin route protection middleware
- Public content display on commune page
- Vote confirmation page link fix

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/app/layouts/default.vue

@@ -0,0 +1,96 @@
+<template>
+  <div class="app-layout">
+    <header class="app-header">
+      <div class="container header-inner">
+        <NuxtLink to="/" class="logo">SejeteralO</NuxtLink>
+        <nav class="header-nav">
+          <NuxtLink to="/">Accueil</NuxtLink>
+          <template v-if="authStore.isAuthenticated">
+            <NuxtLink v-if="authStore.isSuperAdmin" to="/admin">Super Admin</NuxtLink>
+            <NuxtLink
+              v-else-if="authStore.isAdmin && authStore.communeSlug"
+              :to="`/admin/communes/${authStore.communeSlug}`"
+            >
+              Gestion commune
+            </NuxtLink>
+            <button class="btn btn-secondary btn-sm" @click="logout">Déconnexion</button>
+          </template>
+        </nav>
+      </div>
+    </header>
+    <main class="app-main container">
+      <slot />
+    </main>
+    <footer class="app-footer">
+      <div class="container">
+        SejeteralO — Outil de démocratie participative pour la tarification de l'eau
+      </div>
+    </footer>
+  </div>
+</template>
+
+<script setup lang="ts">
+const authStore = useAuthStore()
+const router = useRouter()
+
+function logout() {
+  authStore.logout()
+  router.push('/')
+}
+</script>
+
+<style scoped>
+.app-layout {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+}
+
+.app-header {
+  background: var(--color-surface);
+  border-bottom: 1px solid var(--color-border);
+  padding: 0.75rem 0;
+}
+
+.header-inner {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+}
+
+.logo {
+  font-size: 1.25rem;
+  font-weight: 700;
+  color: var(--color-primary);
+}
+
+.logo:hover {
+  text-decoration: none;
+}
+
+.header-nav {
+  display: flex;
+  align-items: center;
+  gap: 1.5rem;
+}
+
+.btn-sm {
+  padding: 0.25rem 0.75rem;
+  font-size: 0.8rem;
+}
+
+.app-main {
+  flex: 1;
+  padding-top: 2rem;
+  padding-bottom: 2rem;
+}
+
+.app-footer {
+  background: var(--color-surface);
+  border-top: 1px solid var(--color-border);
+  padding: 1rem 0;
+  text-align: center;
+  font-size: 0.75rem;
+  color: var(--color-text-muted);
+}
+</style>