feat: add transaction deduplication feature and enhance filtering options in settings and transactions pages

scripts/import-csv-to-db.ts

@@ -239,11 +239,36 @@ async function main() {
       return dateA.localeCompare(dateB);
     });
     
-    // Calculate balance
-    const balance = transactions.reduce((sum, t) => sum + parseAmount(t.amount), 0);
+    // Deduplicate transactions: same amount + same date + same libelle (description)
+    const seenTransactions = new Map<string, CSVTransaction>();
+    const uniqueTransactions: CSVTransaction[] = [];
+    let duplicatesCount = 0;
+    
+    for (const transaction of transactions) {
+      const amount = parseAmount(transaction.amount);
+      const date = parseDate(transaction.date);
+      const description = transaction.libelle.trim();
+      
+      // Create a unique key: date-amount-description
+      const key = `${date}-${amount}-${description}`;
+      
+      if (!seenTransactions.has(key)) {
+        seenTransactions.set(key, transaction);
+        uniqueTransactions.push(transaction);
+      } else {
+        duplicatesCount++;
+      }
+    }
+    
+    if (duplicatesCount > 0) {
+      console.log(`  → ${duplicatesCount} doublons détectés et ignorés (même date, montant, libellé)`);
+    }
+    
+    // Calculate balance from unique transactions
+    const balance = uniqueTransactions.reduce((sum, t) => sum + parseAmount(t.amount), 0);
     
     // Prepare transactions for insertion
-    const dbTransactions = transactions.map((transaction, index) => {
+    const dbTransactions = uniqueTransactions.map((transaction, index) => {
       const amount = parseAmount(transaction.amount);
       const date = parseDate(transaction.date);