feat(media): Phase 8.G noeuds-ecoles + popup RAG info + lien Bonpote + migration Nebius

- CartePensees: noeuds ecole visibles (cercles proportionnels count auteurs, cliquables, emit select-ecole)
- CartePensees: collision D3 ajustee pour repulsion auteurs autour des noeuds ecole
- FicheEcole: nouveau composant modal (liste auteurs ingeres/non-ingeres, interroger RAG)
- media: header lien Bonpote V2 cliquable + bouton i info RAG
- media: popup FRACAS (description RAG, 662 dimensions, 3 couches, localStorage 1ere visite)
- media: FicheEcole branchee (select-ecole, select-auteur-from-ecole, interroger-ecole)
- ChatbotPensees: suppression mention corpusCount hardcoded (double source de verite)
- chatbot, chatbot-v2, chatbot-reseaux, chatbot-taff: migration Mistral -> Nebius DeepSeek-V3.2
- nuxt.config: ajout nebiusApiKey runtime config

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

server/api/chatbot-reseaux.post.ts

@@ -82,18 +82,18 @@ export default defineEventHandler(async (event) => {
 
   const systemPrompt = SYSTEM_PROMPT.replace('{{STRUCTURES_JSON}}', JSON.stringify(context, null, 0))
 
-  const mistralApiKey = config.mistralApiKey as string
-  if (!mistralApiKey) throw createError({ statusCode: 500, message: 'Clé API Mistral manquante.' })
+  const nebiusApiKey = config.nebiusApiKey as string
+  if (!nebiusApiKey) throw createError({ statusCode: 500, message: 'Clé API Nebius manquante.' })
 
   let mistralRaw: string
   try {
     const res = await $fetch<{ choices: { message: { content: string } }[] }>(
-      'https://api.mistral.ai/v1/chat/completions',
+      'https://api.tokenfactory.nebius.com/v1/chat/completions',
       {
         method: 'POST',
-        headers: { Authorization: `Bearer ${mistralApiKey}`, 'Content-Type': 'application/json' },
+        headers: { Authorization: `Bearer ${nebiusApiKey}`, 'Content-Type': 'application/json' },
         body: JSON.stringify({
-          model: 'mistral-small-latest',
+          model: 'deepseek-ai/DeepSeek-V3.2',
           temperature: 0.3,
           max_tokens: 700,
           response_format: { type: 'json_object' },