Refonte design : 4 humeurs, onboarding, sections avec boite a outils

- Systeme de themes adaptatifs : Peps (light chaud), Zen (light calme),
  Chagrine (dark violet), Grave (dark ambre) avec CSS custom properties
- Dashboard d'accueil orienté onboarding avec cartes-portes et teaser
  boite a outils
- SectionLayout reutilisable : liste + sidebar toolbox + status pills
  cliquables (En prepa / En vote / En vigueur / Clos)
- ToolboxVignette : vignettes Contexte / Tutos / Choisir / Demarrer
- Seed : Acte engagement certification + forgeron, Runtime Upgrade
  (decision on-chain), 3 modalites de vote (majoritaire, quadratique,
  permanent)
- Backend adapte SQLite (Uuid portable, 204 fix, pool conditionnel)
- Correction noms composants (pathPrefix: false), pinia/nuxt ^0.11

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

frontend/app/components/common/MoodSwitcher.vue

@@ -0,0 +1,54 @@
+<script setup lang="ts">
+const { currentMood, moods, setMood } = useMood()
+</script>
+
+<template>
+  <div class="flex items-center gap-1" role="radiogroup" aria-label="Ambiance visuelle">
+    <UTooltip
+      v-for="mood in moods"
+      :key="mood.id"
+      :text="`${mood.label} — ${mood.description}`"
+    >
+      <button
+        type="button"
+        role="radio"
+        :aria-checked="currentMood === mood.id"
+        :aria-label="`Ambiance ${mood.label}`"
+        class="mood-btn"
+        :class="{ 'mood-btn--active': currentMood === mood.id }"
+        @click="setMood(mood.id)"
+      >
+        <UIcon :name="mood.icon" class="text-base" />
+      </button>
+    </UTooltip>
+  </div>
+</template>
+
+<style scoped>
+.mood-btn {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 2rem;
+  height: 2rem;
+  border-radius: 9999px;
+  border: 2px solid transparent;
+  background: var(--mood-surface, #f3f4f6);
+  color: var(--mood-text-muted, #6b7280);
+  cursor: pointer;
+  transition: all 0.2s ease;
+}
+
+.mood-btn:hover {
+  background: var(--mood-surface-hover, #e5e7eb);
+  color: var(--mood-accent, #4b5563);
+  transform: scale(1.1);
+}
+
+.mood-btn--active {
+  border-color: var(--mood-accent, #3b82f6);
+  color: var(--mood-accent, #3b82f6);
+  background: var(--mood-accent-soft, #eff6ff);
+  box-shadow: 0 0 0 2px var(--mood-shadow, rgba(59, 130, 246, 0.15));
+}
+</style>