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/brainstorm/[sessionId]/manual-idea/route.ts

@@ -2,10 +2,20 @@ import { NextRequest, NextResponse } from 'next/server'
 import prisma from '@/lib/prisma'
 import { auth } from '@/auth'
 import { z } from 'zod'
-import { verifyParticipant, logActivity, resolveAiContextUserId, captureSnapshot } from '@/lib/brainstorm-collab'
+import {
+  billingOwnerFromSession,
+  verifyParticipant,
+  logActivity,
+  resolveAiContextUserId,
+  captureSnapshot,
+} from '@/lib/brainstorm-collab'
 import { embeddingService } from '@/lib/ai/services/embedding.service'
-import { getTagsProvider } from '@/lib/ai/factory'
+import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user'
 import { getSystemConfig } from '@/lib/config'
+import {
+  reserveUsageOrThrow,
+  QuotaExceededError,
+} from '@/lib/entitlements'
 import { emitToSession } from '@/lib/socket-emit'
 
 const manualSchema = z.object({
@@ -43,6 +53,11 @@ export async function POST(
       return NextResponse.json({ error: 'Session not found' }, { status: 404 })
     }
 
+    const { billingOwnerId, isGuestActor } = billingOwnerFromSession(
+      brainstormSession.userId,
+      session.user.id,
+    )
+
     let wave = 1
     let parentIdea: any = null
     if (parentIdeaId) {
@@ -78,8 +93,25 @@ export async function POST(
       },
     })
 
-    // [UPDATE - SÉCURITÉ] Recherche vectorielle guest-safe
+    // Story 3.5: per-provider BYOK bypass for enrich
+    let enrichBlocked = false
+    try {
+      const config = await getSystemConfig()
+      const { usedByok: willUseByok } = await willUseByokForLane('tags', config, billingOwnerId)
+      if (!willUseByok) {
+        await reserveUsageOrThrow(billingOwnerId, 'brainstorm_enrich')
+      }
+    } catch (err) {
+      if (err instanceof QuotaExceededError) {
+        enrichBlocked = true
+      } else {
+        console.error('[manual-idea] reserveUsage error:', err)
+      }
+    }
+
+    // [UPDATE - SÉCURITÉ] Recherche vectorielle guest-safe (skipped when host quota exhausted)
     let relatedNoteIds: string[] = []
+    if (!enrichBlocked) {
     try {
       const { isGuest, publicNoteIds, aiUserId } = await resolveAiContextUserId(sessionId, session.user.id)
 
@@ -117,7 +149,10 @@ export async function POST(
         }
         relatedNoteIds = results.map((r: any) => r.id)
       }
-    } catch {}
+    } catch (vectorErr) {
+      console.error('[manual-idea] vector context search failed:', vectorErr)
+    }
+    }
 
     if (relatedNoteIds.length > 0) {
       const notes = await prisma.note.findMany({
@@ -155,6 +190,16 @@ export async function POST(
     const requestingUserId = session.user!.id
 
     const enrichAsync = async () => {
+      if (enrichBlocked) {
+        await emitToSession(sessionId, 'idea:ai_failed', {
+          ideaId: idea.id,
+          reason: 'quota_exceeded',
+          isGuestActor,
+          billingOwnerId,
+        })
+        return
+      }
+
       try {
         // Notifier le room que l'IA traite ce nœud (bordure pulsante violet)
         await emitToSession(sessionId, 'idea:ai_processing', {
@@ -163,7 +208,6 @@ export async function POST(
         })
 
         const config = await getSystemConfig()
-        const provider = getTagsProvider(config)
         const lang = locale === 'fr' ? 'French' : locale === 'es' ? 'Spanish' : locale === 'de' ? 'German' : locale === 'it' ? 'Italian' : locale === 'pt' ? 'Portuguese' : locale === 'ja' ? 'Japanese' : locale === 'ko' ? 'Korean' : locale === 'zh' ? 'Chinese' : locale === 'ar' ? 'Arabic' : "the user's language"
 
         const enrichPrompt = `You are an idea enrichment assistant. Given a user's raw brainstorm idea and context, produce a JSON object with:
@@ -181,7 +225,12 @@ User's raw description: "${description || 'none provided'}"
 
 Respond ONLY with the JSON object, no markdown.`
 
-        const raw = await provider.generateText(enrichPrompt)
+        const { result: raw } = await runLaneWithBillingUser(
+          'tags',
+          config,
+          billingOwnerId,
+          (provider) => provider.generateText(enrichPrompt),
+        )
         const cleaned = raw.replace(/```json\n?/g, '').replace(/```\n?/g, '').trim()
         const enriched = JSON.parse(cleaned)
 
@@ -195,7 +244,6 @@ Respond ONLY with the JSON object, no markdown.`
           data: { title: enrichedTitle, description: enrichedDescription, connectionToSeed, noveltyScore },
         })
 
-        // [UPDATE - TEMPS RÉEL] Notifier la complétion avec les données enrichies
         await emitToSession(sessionId, 'idea:ai_completed', {
           ideaId: idea.id,
           title: enrichedTitle,