feat: extract MediaController, wire into Dispatcher, delete media.php

app/public/admin/actions/export-csv.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * Export TFE listings as CSV.
+ *
+ * Thin dispatcher — delegates all data assembly to ExportController,
+ * then streams the response.
+ */
+require_once __DIR__ . "/../../../bootstrap.php";
+require_once __DIR__ . '/../../../src/AdminAuth.php';
+AdminAuth::requireLogin();
+
+require_once APP_ROOT . '/src/Controllers/ExportController.php';
+$controller = ExportController::create();
+
+$filename = 'posterg-export-' . date('Y-m-d') . '.csv';
+
+header('Content-Type: text/csv; charset=UTF-8');
+header('Content-Disposition: attachment; filename="' . $filename . '"');
+header('Cache-Control: no-cache, must-revalidate');
+
+// UTF-8 BOM for Excel compatibility
+echo "\xEF\xBB\xBF";
+
+$out = fopen('php://output', 'w');
+
+// Column headers
+fputcsv($out, ExportController::CSV_HEADERS, ',', '"', '');
+
+// Data rows
+$rows = $controller->exportAllTheses();
+foreach ($rows as $csvLine) {
+    fputcsv($out, $csvLine, ',', '"', '');
+}
+
+fclose($out);
+exit;