feat(feedback): thumbs up/down + missed-items widget across all tools

New api/feedback.php stores rating + correction text to tool_feedback
table in bnl_admin. renderFeedbackWidget() appended to all tool results
(timeline, redact, transcribe, ask, summarize, search). Thumbs reveal
a textarea for missed/wrong items on click; submit POSTs asynchronously.
Engine from last run is stored alongside the rating.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/feedback.php

@@ -0,0 +1,42 @@
+<?php
+declare(strict_types=1);
+
+require_once __DIR__ . '/../includes/bootstrap.php';
+
+dbnToolsRequireMethod('POST');
+dbnToolsRequireAuth();
+
+$input = dbnToolsJsonInput(8000);
+
+$tool   = substr(preg_replace('/[^a-z_]/', '', strtolower((string)($input['tool'] ?? ''))), 0, 30);
+$rating = (string)($input['rating'] ?? '');
+$missed = substr(trim((string)($input['missed_or_wrong'] ?? '')), 0, 2000);
+$engine = substr(preg_replace('/[^a-zA-Z0-9_.() \-]/', '', (string)($input['engine'] ?? '')), 0, 60);
+
+if (!in_array($rating, ['positive', 'negative'], true)) {
+    dbnToolsAbort('Invalid rating value.', 422, 'invalid_rating');
+}
+if ($tool === '') {
+    dbnToolsAbort('Tool name is required.', 422, 'missing_tool');
+}
+
+try {
+    $db   = dbnToolsDb();
+    $stmt = $db->prepare(
+        'INSERT INTO tool_feedback (session_id, tool, rating, missed_or_wrong, engine)
+         VALUES (?, ?, ?, ?, ?)'
+    );
+    $stmt->execute([
+        substr(session_id(), 0, 40) ?: null,
+        $tool,
+        $rating,
+        $missed !== '' ? $missed : null,
+        $engine !== '' ? $engine : null,
+    ]);
+} catch (Throwable $e) {
+    error_log('tool_feedback insert failed: ' . $e->getMessage());
+    dbnToolsAbort('Could not save feedback.', 500, 'db_error');
+}
+
+header('Content-Type: application/json');
+echo json_encode(['ok' => true]);