Error tests, FK violations fix

- ErrorHandler tests: 77 assertions covering FK extraction, normalization, dedup, edge cases. Fix FK table map for child tables.
- Fix FK violation: (int)null → 0 in createThesis for orientation/ap/finality/license FK columns. Add FK value logging to updateThesis.
- Add CURRENT_ISSUES.md with summary of FK violation, dev debugging, and tag dedup status for next conversation

app/src/Controllers/MediaController.php

@@ -53,6 +53,7 @@ class MediaController
         // 3. Visibility gate for thesis files
         if (preg_match('#^theses/#', $requestedPath)) {
             require_once APP_ROOT . '/src/Database.php';
+            require_once APP_ROOT . '/src/ErrorHandler.php';
             try {
                 $mediaDb     = Database::getInstance();
                 $accessTypeId = $mediaDb->getFileVisibility($requestedPath);
@@ -61,7 +62,7 @@ class MediaController
                     exit;
                 }
             } catch (\Throwable $e) {
-                error_log('MediaController visibility check error: ' . $e->getMessage());
+                ErrorHandler::log('media_visibility', $e, ['path' => $path]);
             }
         }