feat: design system overhaul — sidebar, AI chats, settings, brainstorm, color cleanup

- Sidebar: dynamic brand-accent colors, brainstorm section restyled
- AI chat general: popup panel with expand/collapse, hides when contextual AI open
- AI chat contextual: tabs reordered (Actions first), X close button, height fix
- Settings: all tabs restyled, 6 new color presets (sage, terracotta, iron, etc.)
- Global color cleanup: emerald/orange hardcoded → brand-accent dynamic
- Brainstorm page: orange → brand-accent throughout
- PageEntry animation component added to key pages
- Floating AI button: bg-brand-accent instead of hardcoded black
- i18n: all 15 locales updated with new AI/billing keys
- Billing: freemium quota tracking, BYOK, stripe subscription scaffolding
- Admin: integrated into new design
- AGENTS.md + CLAUDE.md project rules added

memento-note/app/api/ai/tags/route.ts

@@ -1,9 +1,10 @@
 import { NextRequest, NextResponse } from 'next/server';
 import { auth } from '@/auth';
 import { contextualAutoTagService } from '@/lib/ai/services/contextual-auto-tag.service';
-import { getTagsProvider } from '@/lib/ai/factory';
+import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user';
 import { getSystemConfig } from '@/lib/config';
 import { z } from 'zod';
+import { checkEntitlementOrThrow, QuotaExceededError, incrementUsageAsync } from '@/lib/entitlements';
 
 import { getAISettings } from '@/app/actions/ai-settings';
 
@@ -25,6 +26,18 @@ export async function POST(req: NextRequest) {
       return NextResponse.json({ tags: [] });
     }
 
+    try {
+      const config = await getSystemConfig();
+      const { usedByok: willUseByok } = await willUseByokForLane('tags', config, session.user.id);
+      if (!willUseByok) {
+        await checkEntitlementOrThrow(session.user.id, 'auto_tag');
+      }
+    } catch (err) {
+      if (err instanceof QuotaExceededError) {
+        return NextResponse.json(err.toJSON(), { status: 402 });
+      }
+      console.error('[/api/ai/tags] Quota check error (fail-open):', err);
+    }
     const body = await req.json();
     const { content, notebookId, language } = requestSchema.parse(body);
 
@@ -58,8 +71,13 @@ export async function POST(req: NextRequest) {
     // Otherwise, use legacy auto-tagging (generates new tags)
     try {
       const config = await getSystemConfig();
-      const provider = getTagsProvider(config);
-      const tags = await provider.generateTags(content, language);
+      const { result: tags, usedByok } = await runLaneWithBillingUser(
+        'tags',
+        config,
+        session.user.id,
+        (provider) => provider.generateTags(content, language),
+      );
+      if (!usedByok) incrementUsageAsync(session.user.id, 'auto_tag');
       return NextResponse.json({ tags });
     } catch (err) {
       console.error('[/api/ai/tags] legacy tagging failed:', err)

memento-note/app/api/ai/title-suggestions/route.ts

@@ -1,8 +1,9 @@
 import { NextRequest, NextResponse } from 'next/server'
-import { getTagsProvider } from '@/lib/ai/factory'
+import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user'
 import { getSystemConfig } from '@/lib/config'
 import { auth } from '@/auth'
 import { getAISettings } from '@/app/actions/ai-settings'
+import { checkEntitlementOrThrow, QuotaExceededError, incrementUsageAsync } from '@/lib/entitlements'
 import { z } from 'zod'
 
 const requestSchema = z.object({
@@ -13,14 +14,27 @@ export async function POST(req: NextRequest) {
   try {
     // Check authentication and user setting
     const session = await auth()
-    if (session?.user?.id) {
-      const settings = await getAISettings(session.user.id)
-      if (settings.titleSuggestions === false) {
-        return NextResponse.json({ suggestions: [] })
-      }
+    if (!session?.user?.id) {
+      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
     }
 
+    const settings = await getAISettings(session.user.id)
+    if (settings.titleSuggestions === false) {
+      return NextResponse.json({ suggestions: [] })
+    }
 
+    try {
+      const config = await getSystemConfig()
+      const { usedByok: willUseByok } = await willUseByokForLane('tags', config, session.user.id);
+      if (!willUseByok) {
+        await checkEntitlementOrThrow(session.user.id, 'auto_title');
+      }
+    } catch (err) {
+      if (err instanceof QuotaExceededError) {
+        return NextResponse.json(err.toJSON(), { status: 402 });
+      }
+      console.error('[/api/ai/title-suggestions] Quota check error (fail-open):', err);
+    }
     const body = await req.json()
     const { content } = requestSchema.parse(body)
 
@@ -35,7 +49,6 @@ export async function POST(req: NextRequest) {
     }
 
     const config = await getSystemConfig()
-    const provider = getTagsProvider(config)
 
     // Détecter la langue du contenu (simple détection basée sur les caractères et mots)
     const hasNonLatinChars = /[\u0400-\u04FF\u0600-\u06FF\u4E00-\u9FFF\u0E00-\u0E7F]/.test(content)
@@ -95,7 +108,13 @@ CONTENT_START: ${content.substring(0, 500)} CONTENT_END
 
 Réponds SEULEMENT avec un tableau JSON: [{"title": "titre1", "confidence": 0.95}, {"title": "titre2", "confidence": 0.85}, {"title": "titre3", "confidence": 0.75}]`
 
-    const titles = await provider.generateTitles(titlePrompt)
+    const { result: titles, usedByok } = await runLaneWithBillingUser(
+      'tags',
+      config,
+      session.user.id,
+      (provider) => provider.generateTitles(titlePrompt),
+    )
+    if (!usedByok) incrementUsageAsync(session.user.id, 'auto_title')
 
     // Créer les suggestions
     const suggestions = titles.map((t: any) => ({