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/lib/ai/services/slide-intent.ts

@@ -0,0 +1,151 @@
+/**
+ * Slide generation intent (Sprint A product layer).
+ * Passed from UI → API → agent.description → generateSlideDeck.
+ */
+
+export type SlidePurpose =
+  | 'auto'
+  | 'course'
+  | 'board'
+  | 'project'
+  | 'strategy'
+  | 'pitch'
+  | 'summary'
+
+export type SlideAudience = 'auto' | 'student' | 'board' | 'team' | 'client' | 'general'
+
+export interface SlideIntent {
+  purpose?: SlidePurpose
+  audience?: SlideAudience
+  /** Target body slides including title+summary, clamped 3–8 */
+  slideCount?: number
+  /** Existing executive template id or auto */
+  template?: string
+}
+
+const PURPOSE_SET = new Set<string>([
+  'auto',
+  'course',
+  'board',
+  'project',
+  'strategy',
+  'pitch',
+  'summary',
+])
+
+const AUDIENCE_SET = new Set<string>([
+  'auto',
+  'student',
+  'board',
+  'team',
+  'client',
+  'general',
+])
+
+export function clampSlideCount(n: unknown): number | undefined {
+  const v = typeof n === 'number' ? n : typeof n === 'string' ? parseInt(n, 10) : NaN
+  if (!Number.isFinite(v)) return undefined
+  return Math.min(8, Math.max(3, Math.round(v)))
+}
+
+export function normalizeSlideIntent(raw: Partial<SlideIntent> | null | undefined): SlideIntent {
+  if (!raw || typeof raw !== 'object') return {}
+  const purpose = raw.purpose && PURPOSE_SET.has(raw.purpose) ? raw.purpose : 'auto'
+  const audience = raw.audience && AUDIENCE_SET.has(raw.audience) ? raw.audience : 'auto'
+  const slideCount = clampSlideCount(raw.slideCount)
+  const template =
+    typeof raw.template === 'string' && raw.template.trim() ? raw.template.trim() : 'auto'
+  return { purpose, audience, slideCount, template }
+}
+
+/** Encode intent into agent.description (backward compatible with template:xxx). */
+export function encodeSlideIntentDescription(intent: SlideIntent): string {
+  const n = normalizeSlideIntent(intent)
+  // Prefer structured JSON for the structured pipeline
+  return `slide-intent:${JSON.stringify(n)}`
+}
+
+/** Decode agent.description → intent */
+export function decodeSlideIntentDescription(description?: string | null): SlideIntent {
+  if (!description) return {}
+  if (description.startsWith('slide-intent:')) {
+    try {
+      return normalizeSlideIntent(JSON.parse(description.slice('slide-intent:'.length)))
+    } catch {
+      return {}
+    }
+  }
+  if (description.startsWith('template:')) {
+    const template = description.replace('template:', '').trim() || 'auto'
+    // Map legacy templates to purpose
+    const purposeMap: Record<string, SlidePurpose> = {
+      'board-update': 'board',
+      'project-status': 'project',
+      'strategy-review': 'strategy',
+      'quarterly-results': 'board',
+    }
+    return normalizeSlideIntent({
+      template,
+      purpose: purposeMap[template] || 'auto',
+    })
+  }
+  return {}
+}
+
+/** Human guidance injected into outline/expand prompts */
+export function intentPromptHints(intent: SlideIntent, lang: 'fr' | 'en'): string {
+  const n = normalizeSlideIntent(intent)
+  const lines: string[] = []
+
+  if (n.purpose && n.purpose !== 'auto') {
+    const mapFr: Record<SlidePurpose, string> = {
+      auto: '',
+      course: 'Type: COURS / leçon — arc pédagogique (définitions → formules → exemples → résumé). Priorité aux slides equation si maths.',
+      board: 'Type: COMITÉ / board — KPIs, décisions, risques, next steps.',
+      project: 'Type: SUIVI PROJET — avancement, blockers, livrables, roadmap.',
+      strategy: 'Type: STRATÉGIE — options, trade-offs, recommandations.',
+      pitch: 'Type: PITCH — problème, solution, preuve, call to action.',
+      summary: 'Type: SYNTHÈSE — peu de slides, dense, takeaways actionnables.',
+    }
+    const mapEn: Record<SlidePurpose, string> = {
+      auto: '',
+      course: 'Type: LESSON — pedagogical arc (defs → formulas → examples → summary). Prefer equation slides for math.',
+      board: 'Type: BOARD — KPIs, decisions, risks, next steps.',
+      project: 'Type: PROJECT STATUS — progress, blockers, deliverables, roadmap.',
+      strategy: 'Type: STRATEGY — options, trade-offs, recommendations.',
+      pitch: 'Type: PITCH — problem, solution, proof, CTA.',
+      summary: 'Type: SUMMARY — few dense slides, actionable takeaways.',
+    }
+    lines.push(lang === 'fr' ? mapFr[n.purpose] : mapEn[n.purpose])
+  }
+
+  if (n.audience && n.audience !== 'auto') {
+    const mapFr: Record<SlideAudience, string> = {
+      auto: '',
+      student: 'Audience: étudiants — clarté, définitions, exemples, formules explicites.',
+      board: 'Audience: comité de direction — concis, chiffres, décisions.',
+      team: 'Audience: équipe — opérationnel, actions, responsabilités.',
+      client: 'Audience: client — bénéfices, preuves, sans jargon interne.',
+      general: 'Audience: grand public — langage simple.',
+    }
+    const mapEn: Record<SlideAudience, string> = {
+      auto: '',
+      student: 'Audience: students — clarity, definitions, examples, explicit formulas.',
+      board: 'Audience: board — concise, numbers, decisions.',
+      team: 'Audience: team — operational, actions, ownership.',
+      client: 'Audience: client — benefits, proof, no internal jargon.',
+      general: 'Audience: general — plain language.',
+    }
+    lines.push(lang === 'fr' ? mapFr[n.audience] : mapEn[n.audience])
+  }
+
+  if (n.slideCount) {
+    lines.push(
+      lang === 'fr'
+        ? `Nombre de slides imposé: EXACTEMENT ${n.slideCount} (title + corps + summary inclus).`
+        : `Slide count required: EXACTLY ${n.slideCount} (including title + body + summary).`,
+    )
+  }
+
+  return lines.filter(Boolean).join('\n')
+}