fix: display db timestamps in Brussels time

(heure de dépôt was showing UTC)

- feat: add date_depot column (real TFE deposit date)
with CSV round-trip + Brussels→UTC sanitization
- fix: keep PHP default tz at UTC to preserve token/share-link
 expiry consistency; convert to Brussels only in db_datetime()

app/bootstrap.php

@@ -10,6 +10,42 @@ $autoloadPath = file_exists(__DIR__ . '/vendor/autoload.php')
     : __DIR__ . '/../vendor/autoload.php';
 require_once $autoloadPath;
 
+// The site serves the ERG (Brussels), but the server + SQLite timestamps run in
+// UTC (CURRENT_TIMESTAMP). We intentionally do NOT change the PHP default
+// timezone: code that writes timestamps via date()/time() (e.g. one-time
+// tokens, share-link expiries) must stay wall-clock consistent with SQLite's
+// CURRENT_TIMESTAMP (UTC), otherwise expiries drift by the UTC↔Brussels offset.
+// Conversion to Brussels is handled explicitly at the display layer via
+// db_datetime() below.
+
+/**
+ * Format a database-stored datetime for display in Brussels local time.
+ *
+ * SQLite timestamps (submitted_at, created_at, published_at, …) are written
+ * with CURRENT_TIMESTAMP (= UTC). This parses the value as UTC and converts it
+ * to Europe/Brussels (UTC+1 winter / UTC+2 summer) — independent of the PHP
+ * default timezone, so it never affects DB write/read consistency elsewhere.
+ */
+function db_datetime(string $raw, string $format = 'd/m/Y à H:i'): string
+{
+    if ($raw === '') {
+        return '';
+    }
+
+    $dt = DateTime::createFromFormat('Y-m-d H:i:s', $raw, new DateTimeZone('UTC'));
+    if ($dt === false) {
+        // Non-ISO fallback: parse the naive string as UTC.
+        $ts = strtotime($raw . ' UTC');
+        if ($ts === false) {
+            return $raw;
+        }
+        $dt = (new DateTime('@' . $ts))->setTimezone(new DateTimeZone('UTC'));
+    }
+
+    $dt->setTimezone(new DateTimeZone('Europe/Brussels'));
+    return $dt->format($format);
+}
+
 // Define application root
 define('APP_ROOT', __DIR__);