fix(uploads): reclaim abandoned front-submit attachments

Mark new regular and chunked uploads as pending and claim persisted article references, including partial saves and large reference sets. Protect associated media from cleanup and add upload lifecycle regression coverage.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/widget-system/front-submit-pending-contract.test.cjs

@@ -0,0 +1,12 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const { execFileSync } = require('node:child_process');
+const path = require('node:path');
+const test = require('node:test');
+
+test('front-submit pending upload lifecycle runs against production PHP traits', () => {
+  const harness = path.join(__dirname, 'front-submit-pending-harness.php');
+  const output = execFileSync('php', [harness], { encoding: 'utf8' });
+  assert.match(output, /Front-submit pending behavior harness passed/);
+});