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/route.ts

@@ -2,9 +2,14 @@ import { NextRequest, NextResponse } from 'next/server'
 import prisma from '@/lib/prisma'
 import { auth } from '@/auth'
 import { z } from 'zod'
-import { getTagsProvider } from '@/lib/ai/factory'
+import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user'
 import { getSystemConfig } from '@/lib/config'
 import { embeddingService } from '@/lib/ai/services/embedding.service'
+import {
+  checkEntitlementOrThrow,
+  QuotaExceededError,
+  incrementUsageAsync,
+} from '@/lib/entitlements'
 import { logActivity, captureSnapshot } from '@/lib/brainstorm-collab'
 
 const waveSchema = z.object({
@@ -64,11 +69,7 @@ async function autoContextSearch(
     snippet: (n.content || '').slice(0, 300),
   }))
 
-  try {
-    const config = await getSystemConfig()
-    const provider = getTagsProvider(config)
-
-    const classifyPrompt = `Given the seed idea: "${seedIdea}"
+  const classifyPrompt = `Given the seed idea: "${seedIdea}"
 
 Classify each note as SUPPORT (confirms/reinforces the seed), TENSION (contradicts/questions the seed), or EXTENSION (extends the seed into an adjacent domain).
 
@@ -78,7 +79,14 @@ ${notesForLLM.map(n => `[${n.id}] "${n.title}": ${n.snippet}`).join('\n')}
 Respond ONLY with a valid JSON array of objects:
 { "noteId": string, "category": "SUPPORT" | "TENSION" | "EXTENSION" }`
 
-    const raw = await provider.generateText(classifyPrompt)
+  try {
+    const config = await getSystemConfig()
+    const { result: raw } = await runLaneWithBillingUser(
+      'tags',
+      config,
+      userId,
+      (provider) => provider.generateText(classifyPrompt),
+    )
     const cleaned = raw.replace(/```json\n?/g, '').replace(/```\n?/g, '').trim()
     const classifications: { noteId: string; category: 'SUPPORT' | 'TENSION' | 'EXTENSION' }[] = JSON.parse(cleaned)
 
@@ -199,13 +207,23 @@ export async function POST(request: NextRequest) {
     const body = await request.json()
     const { seedIdea, sourceNoteId, contextNoteIds, locale } = waveSchema.parse(body)
 
+    // Story 3.5: per-provider BYOK bypass
+    const config = await getSystemConfig()
+    const { usedByok: willUseByok } = await willUseByokForLane('tags', config, userId)
+    if (!willUseByok) {
+      await checkEntitlementOrThrow(userId, 'brainstorm_create')
+    }
+
     const classifiedNotes = await autoContextSearch(userId, seedIdea, contextNoteIds)
 
-    const config = await getSystemConfig()
-    const provider = getTagsProvider(config)
-
     const prompt = buildPromptV2(seedIdea, classifiedNotes, locale)
-    const llmResponse = await provider.generateText(prompt)
+    const { result: llmResponse, usedByok } = await runLaneWithBillingUser(
+      'tags',
+      config,
+      userId,
+      (provider) => provider.generateText(prompt),
+    )
+    if (!usedByok) incrementUsageAsync(userId, 'brainstorm_create')
 
     let ideas: any[]
     try {
@@ -312,6 +330,9 @@ export async function POST(request: NextRequest) {
       },
     }, { status: 201 })
   } catch (error: any) {
+    if (error instanceof QuotaExceededError) {
+      return NextResponse.json(error.toJSON(), { status: 402 })
+    }
     if (error instanceof z.ZodError) {
       return NextResponse.json({ error: error.issues }, { status: 400 })
     }