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/actions/ai-settings.ts

@@ -0,0 +1,140 @@
+'use server'
+
+import { auth } from '@/auth'
+import { prisma } from '@/lib/prisma'
+import { revalidatePath } from 'next/cache'
+
+export type UserAISettingsData = {
+  titleSuggestions?: boolean
+  semanticSearch?: boolean
+  paragraphRefactor?: boolean
+  memoryEcho?: boolean
+  memoryEchoFrequency?: 'daily' | 'weekly' | 'custom'
+  aiProvider?: 'auto' | 'openai' | 'ollama'
+  preferredLanguage?: 'auto' | 'en' | 'fr' | 'es' | 'de' | 'fa' | 'it' | 'pt' | 'ru' | 'zh' | 'ja' | 'ko' | 'ar' | 'hi' | 'nl' | 'pl'
+  demoMode?: boolean
+}
+
+/**
+ * Update AI settings for the current user
+ */
+export async function updateAISettings(settings: UserAISettingsData) {
+  const session = await auth()
+  if (!session?.user?.id) {
+    throw new Error('Unauthorized')
+  }
+
+  try {
+    // Upsert settings (create if not exists, update if exists)
+    await prisma.userAISettings.upsert({
+      where: { userId: session.user.id },
+      create: {
+        userId: session.user.id,
+        ...settings
+      },
+      update: settings
+    })
+
+    revalidatePath('/settings/ai')
+    revalidatePath('/')
+
+    return { success: true }
+  } catch (error) {
+    console.error('Error updating AI settings:', error)
+    throw new Error('Failed to update AI settings')
+  }
+}
+
+/**
+ * Get AI settings for the current user
+ */
+export async function getAISettings() {
+  const session = await auth()
+
+  // Return defaults for non-logged-in users
+  if (!session?.user?.id) {
+    return {
+      titleSuggestions: true,
+      semanticSearch: true,
+      paragraphRefactor: true,
+      memoryEcho: true,
+      memoryEchoFrequency: 'daily' as const,
+      aiProvider: 'auto' as const,
+      preferredLanguage: 'auto' as const,
+      demoMode: false
+    }
+  }
+
+  try {
+    const settings = await prisma.userAISettings.findUnique({
+      where: { userId: session.user.id }
+    })
+
+    // Return settings or defaults if not found
+    if (!settings) {
+      return {
+        titleSuggestions: true,
+        semanticSearch: true,
+        paragraphRefactor: true,
+        memoryEcho: true,
+        memoryEchoFrequency: 'daily' as const,
+        aiProvider: 'auto' as const,
+        preferredLanguage: 'auto' as const,
+        demoMode: false
+      }
+    }
+
+    // Type-cast database values to proper union types
+    return {
+      titleSuggestions: settings.titleSuggestions,
+      semanticSearch: settings.semanticSearch,
+      paragraphRefactor: settings.paragraphRefactor,
+      memoryEcho: settings.memoryEcho,
+      memoryEchoFrequency: (settings.memoryEchoFrequency || 'daily') as 'daily' | 'weekly' | 'custom',
+      aiProvider: (settings.aiProvider || 'auto') as 'auto' | 'openai' | 'ollama',
+      preferredLanguage: (settings.preferredLanguage || 'auto') as 'auto' | 'en' | 'fr' | 'es' | 'de' | 'fa' | 'it' | 'pt' | 'ru' | 'zh' | 'ja' | 'ko' | 'ar' | 'hi' | 'nl' | 'pl',
+      demoMode: settings.demoMode || false
+    }
+  } catch (error) {
+    console.error('Error getting AI settings:', error)
+    // Return defaults on error
+    return {
+      titleSuggestions: true,
+      semanticSearch: true,
+      paragraphRefactor: true,
+      memoryEcho: true,
+      memoryEchoFrequency: 'daily' as const,
+      aiProvider: 'auto' as const,
+      preferredLanguage: 'auto' as const,
+      demoMode: false
+    }
+  }
+}
+
+/**
+ * Get user's preferred AI provider
+ */
+export async function getUserAIPreference(): Promise<'auto' | 'openai' | 'ollama'> {
+  const settings = await getAISettings()
+  return settings.aiProvider
+}
+
+/**
+ * Check if a specific AI feature is enabled for the user
+ */
+export async function isAIFeatureEnabled(feature: keyof UserAISettingsData): Promise<boolean> {
+  const settings = await getAISettings()
+
+  switch (feature) {
+    case 'titleSuggestions':
+      return settings.titleSuggestions
+    case 'semanticSearch':
+      return settings.semanticSearch
+    case 'paragraphRefactor':
+      return settings.paragraphRefactor
+    case 'memoryEcho':
+      return settings.memoryEcho
+    default:
+      return true
+  }
+}