Sprint 3 : protocoles de vote et boite a outils

Backend:
- Sessions de vote : list, close, tally, threshold details, auto-expiration
- Protocoles : update, simulate, meta-gouvernance, formulas CRUD
- Service vote enrichi : close_session, get_threshold_details, nuanced breakdown
- Schemas : ThresholdDetailOut, VoteResultOut, FormulaSimulationRequest/Result
- WebSocket broadcast sur chaque vote + fermeture session
- 25 nouveaux tests (threshold details, close, nuanced, simulation)

Frontend:
- 5 composants vote : VoteBinary, VoteNuanced, ThresholdGauge, FormulaDisplay, VoteHistory
- 3 composants protocoles : ProtocolPicker, FormulaEditor, ModeParamsDisplay
- Simulateur de formules interactif (page /protocols/formulas)
- Page detail protocole (/protocols/[id])
- Composable useWebSocket (live updates)
- Composable useVoteFormula (calcul client-side reactif)
- Integration KaTeX pour rendu LaTeX des formules

Documentation:
- API reference : 8 nouveaux endpoints documentes
- Formules : tables d'inertie, parametres detailles, simulation API
- Guide vote : vote binaire/nuance, jauge, historique, simulateur, meta-gouvernance

55 tests passes (+ 1 skipped), 126 fichiers total.

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

frontend/app/components/protocols/ProtocolPicker.vue

@@ -0,0 +1,64 @@
+<script setup lang="ts">
+/**
+ * Dropdown/select to pick a voting protocol.
+ *
+ * Fetches protocols from the store and renders them in a USelect
+ * with protocol name, mode params, and vote type badge.
+ */
+import type { VotingProtocol } from '~/stores/protocols'
+
+const props = defineProps<{
+  modelValue: string | null
+  voteType?: string
+}>()
+
+const emit = defineEmits<{
+  'update:modelValue': [value: string | null]
+}>()
+
+const protocols = useProtocolsStore()
+
+onMounted(async () => {
+  if (protocols.protocols.length === 0) {
+    await protocols.fetchProtocols(props.voteType ? { vote_type: props.voteType } : undefined)
+  }
+})
+
+const filteredProtocols = computed(() => {
+  if (!props.voteType) return protocols.protocols
+  return protocols.protocols.filter(p => p.vote_type === props.voteType)
+})
+
+const options = computed(() => {
+  return filteredProtocols.value.map(p => ({
+    label: buildLabel(p),
+    value: p.id,
+  }))
+})
+
+function buildLabel(p: VotingProtocol): string {
+  const typeLabel = p.vote_type === 'binary' ? 'Binaire' : 'Nuance'
+  const params = p.mode_params ? ` [${p.mode_params}]` : ''
+  return `${p.name} - ${typeLabel}${params}`
+}
+
+function onSelect(value: string) {
+  emit('update:modelValue', value || null)
+}
+</script>
+
+<template>
+  <div>
+    <USelect
+      :model-value="modelValue ?? undefined"
+      :items="options"
+      placeholder="Selectionnez un protocole..."
+      :loading="protocols.loading"
+      value-key="value"
+      @update:model-value="onSelect"
+    />
+    <p v-if="protocols.error" class="text-xs text-red-500 mt-1">
+      {{ protocols.error }}
+    </p>
+  </div>
+</template>