feat: integrate emoji-mart and refactor emoji usage

- Added @emoji-mart/data and @emoji-mart/react dependencies for enhanced emoji support.
- Replaced static emoji characters with Emoji component in various UI components for consistency and improved rendering.
- Updated generateDateTitle function to return an object with emoji and text for better structure.
- Marked the task for removing emojis from the UI as complete in TODO.md.

src/components/dashboard/ProductivityAnalytics.tsx

@@ -9,6 +9,7 @@ import { WeeklyStatsCard } from '@/components/charts/WeeklyStatsCard';
 import { TagDistributionChart } from '@/components/dashboard/TagDistributionChart';
 import { Card, MetricCard } from '@/components/ui';
 import { DeadlineOverview } from '@/components/deadline/DeadlineOverview';
+import { Emoji } from '@/components/ui/Emoji';
 
 interface ProductivityAnalyticsProps {
   metrics: ProductivityMetrics;
@@ -90,7 +91,7 @@ export function ProductivityAnalytics({ metrics, deadlineMetrics, tagMetrics, se
 
       {/* Titre de section Analytics */}
       <div className="flex items-center justify-between">
-        <h2 className="text-2xl font-bold">📊 Analytics & Métriques</h2>
+        <h2 className="text-2xl font-bold"><Emoji emoji="📊" size={20} /> Analytics & Métriques</h2>
         <div className="text-sm text-[var(--muted-foreground)]">
           Derniers 30 jours
         </div>
@@ -141,7 +142,7 @@ export function ProductivityAnalytics({ metrics, deadlineMetrics, tagMetrics, se
 
       {/* Insights automatiques */}
       <Card variant="glass" className="p-6">
-        <h3 className="text-lg font-semibold mb-4">💡 Insights</h3>
+        <h3 className="text-lg font-semibold mb-4"><Emoji emoji="💡" size={25} /> Insights</h3>
         <div className="grid grid-cols-1 md:grid-cols-3 gap-4">
           <MetricCard
             title="Vélocité Moyenne"