fix(quotas): unifier le décompte IA (BYOK, rollback) et combler les fuites

Centralise la réserve via ai-quota, corrige admin unavailable (-1), brancher les routes sans quota et le host-pays brainstorm, avec usage-meter élargi, noms de clusters, MCP et ajustements dashboard/insights.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/app/api/mobile/ai/transcribe/route.ts

@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from 'next/server'
 import { getMobileUserId } from '@/lib/mobile-auth'
 import { getSystemConfig } from '@/lib/config'
+import { reserveUsageOrThrow, QuotaExceededError } from '@/lib/entitlements'
 
 export async function POST(req: NextRequest) {
   const userId = await getMobileUserId(req)
@@ -18,6 +19,15 @@ export async function POST(req: NextRequest) {
   const apiKey = config.OPENAI_API_KEY
   if (!apiKey) return NextResponse.json({ error: 'Service non disponible' }, { status: 503 })
 
+  try {
+    await reserveUsageOrThrow(userId, 'voice_transcribe')
+  } catch (err) {
+    if (err instanceof QuotaExceededError) {
+      return NextResponse.json(err.toJSON(), { status: 429 })
+    }
+    throw err
+  }
+
   const whisperForm = new FormData()
   whisperForm.append('file', file, 'audio.m4a')
   whisperForm.append('model', 'whisper-1')