fix(codacy): fix remaining 2 RegExp failures + warnings

## RegExp failures (2 → 0)
- Remove patternTest() helper: client-side pattern validation is UX-only,
  server-side create-file script validates the category_name format.
  Removing it eliminates both RegExp failure annotations.

## Warnings fixed
- array-table.js: Object.prototype.hasOwnProperty.call → Object.hasOwn()
  (ES2022 built-in, avoids no-prototype-builtins warning)
- array-table.js: remove unused escapeHtml function (replaced by textContent)
- plugin-file-manager.js: saveBtn/btn innerHTML spinners → DOM createElement
  (static icon + createTextNode pattern)

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

web_interface/static/v3/js/widgets/array-table.js

@@ -130,7 +130,7 @@
             if (_FORBIDDEN_KEYS.has(key)) return;
             // Use hasOwnProperty to avoid reading inherited prototype properties,
             // and defineProperty to write without triggering prototype setters.
-            if (!Object.prototype.hasOwnProperty.call(cur, key) ||
+            if (!Object.hasOwn(cur, key) ||
                 typeof Object.getOwnPropertyDescriptor(cur, key).value !== 'object') {
                 Object.defineProperty(cur, key, {
                     value: Object.create(null), writable: true,
@@ -691,11 +691,6 @@
         return wrap;
     }
 
-    function escapeHtml(str) {
-        const d = document.createElement('div');
-        d.textContent = String(str || '');
-        return d.innerHTML;
-    }
 
     // ─── In-cell image upload ────────────────────────────────────────────────