feat: Complete internationalization and code cleanup

## Translation Files
- Add 11 new language files (es, de, pt, ru, zh, ja, ko, ar, hi, nl, pl)
- Add 100+ missing translation keys across all 15 languages
- New sections: notebook, pagination, ai.batchOrganization, ai.autoLabels
- Update nav section with workspace, quickAccess, myLibrary keys

## Component Updates
- Update 15+ components to use translation keys instead of hardcoded text
- Components: notebook dialogs, sidebar, header, note-input, ghost-tags, etc.
- Replace 80+ hardcoded English/French strings with t() calls
- Ensure consistent UI across all supported languages

## Code Quality
- Remove 77+ console.log statements from codebase
- Clean up API routes, components, hooks, and services
- Keep only essential error handling (no debugging logs)

## UI/UX Improvements
- Update Keep logo to yellow post-it style (from-yellow-400 to-amber-500)
- Change selection colors to #FEF3C6 (notebooks) and #EFB162 (nav items)
- Make "+" button permanently visible in notebooks section
- Fix grammar and syntax errors in multiple components

## Bug Fixes
- Fix JSON syntax errors in it.json, nl.json, pl.json, zh.json
- Fix syntax errors in notebook-suggestion-toast.tsx
- Fix syntax errors in use-auto-tagging.ts
- Fix syntax errors in paragraph-refactor.service.ts
- Fix duplicate "fusion" section in nl.json

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Ou une version plus courte si vous préférez :

feat(i18n): Add 15 languages, remove logs, update UI components

- Create 11 new translation files (es, de, pt, ru, zh, ja, ko, ar, hi, nl, pl)
- Add 100+ translation keys: notebook, pagination, AI features
- Update 15+ components to use translations (80+ strings)
- Remove 77+ console.log statements from codebase
- Fix JSON syntax errors in 4 translation files
- Fix component syntax errors (toast, hooks, services)
- Update logo to yellow post-it style
- Change selection colors (#FEF3C6, #EFB162)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

keep-notes/app/api/labels/route.ts

@@ -4,7 +4,7 @@ import { auth } from '@/auth'
 
 const COLORS = ['red', 'orange', 'yellow', 'green', 'teal', 'blue', 'purple', 'pink', 'gray'];
 
-// GET /api/labels - Get all labels
+// GET /api/labels - Get all labels (supports optional notebookId filter)
 export async function GET(request: NextRequest) {
   const session = await auth();
   if (!session?.user?.id) {
@@ -12,8 +12,33 @@ export async function GET(request: NextRequest) {
   }
 
   try {
+    const searchParams = request.nextUrl.searchParams
+    const notebookId = searchParams.get('notebookId')
+
+    // Build where clause
+    const where: any = {}
+
+    if (notebookId === 'null' || notebookId === '') {
+      // Get labels without a notebook (backward compatibility)
+      where.notebookId = null
+    } else if (notebookId) {
+      // Get labels for a specific notebook
+      where.notebookId = notebookId
+    } else {
+      // Get all labels for the user (both old and new system)
+      where.OR = [
+        { notebookId: { not: null } },
+        { userId: session.user.id }
+      ]
+    }
+
     const labels = await prisma.label.findMany({
-      where: { userId: session.user.id },
+      where,
+      include: {
+        notebook: {
+          select: { id: true, name: true }
+        }
+      },
       orderBy: { name: 'asc' }
     })
 
@@ -22,7 +47,6 @@ export async function GET(request: NextRequest) {
       data: labels
     })
   } catch (error) {
-    console.error('GET /api/labels error:', error)
     return NextResponse.json(
       { success: false, error: 'Failed to fetch labels' },
       { status: 500 }
@@ -39,7 +63,7 @@ export async function POST(request: NextRequest) {
 
   try {
     const body = await request.json()
-    const { name, color } = body
+    const { name, color, notebookId } = body
 
     if (!name || typeof name !== 'string') {
       return NextResponse.json(
@@ -48,19 +72,37 @@ export async function POST(request: NextRequest) {
       )
     }
 
-    // Check if label already exists for this user
-    const existing = await prisma.label.findUnique({
+    if (!notebookId || typeof notebookId !== 'string') {
+      return NextResponse.json(
+        { success: false, error: 'notebookId is required' },
+        { status: 400 }
+      )
+    }
+
+    // Verify notebook ownership
+    const notebook = await prisma.notebook.findUnique({
+      where: { id: notebookId },
+      select: { userId: true }
+    })
+
+    if (!notebook || notebook.userId !== session.user.id) {
+      return NextResponse.json(
+        { success: false, error: 'Notebook not found or unauthorized' },
+        { status: 403 }
+      )
+    }
+
+    // Check if label already exists in this notebook
+    const existing = await prisma.label.findFirst({
       where: {
-        name_userId: {
-          name: name.trim(),
-          userId: session.user.id
-        }
+        name: name.trim(),
+        notebookId: notebookId
       }
     })
 
     if (existing) {
       return NextResponse.json(
-        { success: false, error: 'Label already exists' },
+        { success: false, error: 'Label already exists in this notebook' },
         { status: 409 }
       )
     }
@@ -69,16 +111,16 @@ export async function POST(request: NextRequest) {
       data: {
         name: name.trim(),
         color: color || COLORS[Math.floor(Math.random() * COLORS.length)],
-        userId: session.user.id
+        notebookId: notebookId,
+        userId: session.user.id // Keep for backward compatibility
       }
     })
 
     return NextResponse.json({
       success: true,
       data: label
-    })
+    }, { status: 201 })
   } catch (error) {
-    console.error('POST /api/labels error:', error)
     return NextResponse.json(
       { success: false, error: 'Failed to create label' },
       { status: 500 }