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/AboutController.php

@@ -2,6 +2,7 @@
 
 require_once APP_ROOT . '/src/Database.php';
 require_once APP_ROOT . '/src/Parsedown.php';
+require_once APP_ROOT . '/src/ErrorHandler.php';
 
 class AboutController
 {
@@ -24,7 +25,7 @@ class AboutController
             $contacts   = $db->getAproposContent('contacts');
             $contacts   = is_array($contacts) && !empty($contacts) ? $contacts : null;
         } catch (Exception $e) {
-            error_log('Error loading about page: ' . $e->getMessage());
+            ErrorHandler::log('about_page', $e);
             $rawContent = $this->defaultContent;
             $contacts   = null;
         }