Add CSRF protection to declaration creation form

Security Fixes:
- Added CSRF token field to form
- Added token validation in form processing
- Added proper error handling for missing dates
- Added ErrorMissingDates translation in both languages
- Form now properly validates CSRF tokens before processing

This fixes the 'Token not provided' error when submitting the form.

declarationtva_create.php

@@ -45,7 +45,11 @@ $end_date = GETPOST('end_date', 'alpha');
 $error = '';
 $success = '';
 
-if ($action == 'create' && !empty($start_date) && !empty($end_date)) {
+if ($action == 'create') {
+    // Check CSRF token
+    if (!checkToken()) {
+        $error = $langs->trans("ErrorCSRFToken");
+    } elseif (!empty($start_date) && !empty($end_date)) {
         // Create the declaration with dates
         $declaration_id = $declarationtva->createDeclarationWithDates($start_date, $end_date, $declaration_name);
         
@@ -57,6 +61,9 @@ if ($action == 'create' && !empty($start_date) && !empty($end_date)) {
         } else {
             $error = $langs->trans("ErrorCreatingDeclaration") . ": " . $declarationtva->error;
         }
+    } else {
+        $error = $langs->trans("ErrorMissingDates");
+    }
 }
 
 // Page title
@@ -80,6 +87,7 @@ print '<div class="titre">' . $langs->trans("DeclarationDetails") . '</div>';
 
 print '<form method="POST" action="' . $_SERVER['PHP_SELF'] . '">';
 print '<input type="hidden" name="action" value="create">';
+print '<input type="hidden" name="token" value="' . newToken() . '">';
 
 print '<table class="noborder centpercent">';
 

langs/en_US/declarationtva.lang

@@ -402,6 +402,7 @@ DeclarationSubmitted = Declaration submitted successfully
 ErrorCreatingDeclaration = Error creating declaration
 ErrorValidatingDeclaration = Error validating declaration
 ErrorSubmittingDeclaration = Error submitting declaration
+ErrorMissingDates = Please provide both start and end dates
 
 # Create Declaration Page
 DeclarationDetails = Declaration Details

langs/fr_FR/declarationtva.lang

@@ -391,6 +391,7 @@ DeclarationSubmitted = Déclaration soumise avec succès
 ErrorCreatingDeclaration = Erreur lors de la création de la déclaration
 ErrorValidatingDeclaration = Erreur lors de la validation de la déclaration
 ErrorSubmittingDeclaration = Erreur lors de la soumission de la déclaration
+ErrorMissingDates = Veuillez fournir les dates de début et de fin
 
 # Create Declaration Page
 DeclarationDetails = Détails de la déclaration