feat(credits): solde IA unique (option M), packs Stripe et polish billing

Un pot de crédits global (BASIC 100 / PRO 1 000 / BUSINESS 4 000) remplace
les seaux par fonction côté débit. Packs one-shot S/M/L, admin sans seaux
legacy, usage multi-features, hints de coût, anti-flash thème et hydratation
admin. Inclut aussi le pipeline slides renforcé et la page publique polishée.

memento-note/app/actions/admin-billing.ts

@@ -19,6 +19,9 @@ const BILLING_CONFIG_KEYS = [
   'STRIPE_PRICE_PRO_ANNUAL',
   'STRIPE_PRICE_BUSINESS_MONTHLY',
   'STRIPE_PRICE_BUSINESS_ANNUAL',
+  'STRIPE_PRICE_CREDITS_S',
+  'STRIPE_PRICE_CREDITS_M',
+  'STRIPE_PRICE_CREDITS_L',
 ] as const
 
 const TIERS: TierType[] = ['BASIC', 'PRO', 'BUSINESS', 'ENTERPRISE']
@@ -54,7 +57,42 @@ export async function getBillingAdminData() {
     BILLING_CONFIG_KEYS.map((key) => [key, config[key] ?? '']),
   )
 
-  return { entitlements, billingConfig, usageOverview, features: [...VALID_FEATURES], tiers: TIERS }
+  const { CREDIT_ALLOCATIONS, CREDIT_COSTS, slideGenerateCreditCost } = await import('@/lib/credits')
+  const { CREDIT_PACKS, CREDIT_PACK_IDS } = await import('@/lib/billing/credit-packs')
+
+  const creditAllocations = TIERS.map((tier) => {
+    const raw = CREDIT_ALLOCATIONS[tier]
+    return {
+      tier,
+      monthlyCredits: raw === 'unlimited' ? null : raw,
+      unlimited: raw === 'unlimited',
+    }
+  })
+
+  const creditCosts = {
+    ...CREDIT_COSTS,
+    slide_generate_example: slideGenerateCreditCost(7),
+  }
+
+  const creditPacks = CREDIT_PACK_IDS.map((id) => {
+    const p = CREDIT_PACKS[id]
+    return {
+      id: p.id,
+      credits: p.credits,
+      defaultDisplay: p.defaultDisplay,
+    }
+  })
+
+  return {
+    entitlements,
+    billingConfig,
+    usageOverview,
+    features: [...VALID_FEATURES],
+    tiers: TIERS,
+    creditAllocations,
+    creditCosts,
+    creditPacks,
+  }
 }
 
 export async function updatePlanEntitlement(