feat(tools): owner feedback review surface + tool_feedback migration

Adds the missing migration for the tool_feedback table (dobetternorge_maindb)
that the in-result feedback widget writes to, repoints api/feedback.php to
dbnmDb() for consistency with the engine-config table, and adds an owner-only
dashboard (page + read API + nav) summarising ratings and notes by tool/engine.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

api/feedback.php

@@ -21,7 +21,7 @@ if ($tool === '') {
 }
 
 try {
-    $db   = dbnToolsDb();
+    $db   = dbnmDb();
     $stmt = $db->prepare(
         'INSERT INTO tool_feedback (session_id, tool, rating, missed_or_wrong, engine)
          VALUES (?, ?, ?, ?, ?)'