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-v2.post.ts

@@ -145,19 +145,22 @@ export default defineEventHandler(async (event) => {
 
   const systemPrompt = SYSTEM_PROMPT_V2.replace('{{CONTEXTE_RAG}}', contextStr)
 
-  // 7. Mistral Small - génération réponse
+  // 7. Nebius DeepSeek-V3.2 - génération réponse
+  const nebiusApiKey = config.nebiusApiKey as string
+  if (!nebiusApiKey) throw createError({ statusCode: 500, statusMessage: 'Clé API Nebius manquante.' })
+
   let mistralRaw: string
   try {
-    const mistralRes = await $fetch<{
+    const nebiusRes = 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}`,
+        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: 600,
         response_format: { type: 'json_object' },
@@ -167,10 +170,10 @@ export default defineEventHandler(async (event) => {
         ]
       })
     })
-    mistralRaw = mistralRes.choices?.[0]?.message?.content ?? '{}'
+    mistralRaw = nebiusRes.choices?.[0]?.message?.content ?? '{}'
   } catch (e: any) {
-    console.error('[chatbot-v2] Erreur Mistral Small :', e?.message ?? e)
-    throw createError({ statusCode: 502, statusMessage: 'Erreur appel Mistral Small.' })
+    console.error('[chatbot-v2] Erreur Nebius DeepSeek :', e?.message ?? e)
+    throw createError({ statusCode: 502, statusMessage: 'Erreur appel Nebius DeepSeek.' })
   }
 
   // 8. Parse JSON