Improve audit logging, error handling, and metadata encoding

- Ensure all email/SMS send attempts are audit-logged, including API errors, exceptions, invalid addresses, and disabled service cases; logs now include raw API responses or exception details for better diagnostics.
- Fix audit log parameter builder to never pass NULL for NOT NULL columns (`config`, `DateSent`).
- Add unit tests covering all send paths and audit log correctness.
- Percent-encode non-ASCII/control chars in `DocumentMetadataBuilder` for safe HTTP header metadata; add tests.
- Simplify admin test mail dialog JS and improve success handler robustness.
- Set `charset=utf-8` in admin controller JSON responses for OCORE consistency.
- Update minified JS to match new admin dialog logic.

Fuchs/wwwroot/web/fis.admin.de.js

@@ -315,18 +315,13 @@ let $adm = {
             button: $adt.testmail_btn,
             size: [420, 560],
             addcontent: $$.dc('adm_note').text($adt.tm_hint),
-            submit: function (e) {
-                let c = $(this).ldng(1);
-                let qs = c.serializeObject(true, { typedvalues: true });
-                $ocms.postXT({
-                    url: $ocms.url('admin/testmail'), data: qs, timeout: 60000, success: function (r) {
-                        let res = r.result || {};
-                        alert(res.message || (res.sent ? $adt.tm_sent : $adt.tm_failed));
-                        c.trigger('modal_close');
-                    }, error: function () {
-                        alert($adt.tm_failed);
-                    }, complete: function () { c.ldng(0); }
-                });
+            url: $ocms.url('admin/testmail'),
+            typedvalues: true,
+            /* Runs inside jQuery's success dispatch — it must never throw, or postXT's
+               `complete` (which clears the page loading indicator) is skipped. */
+            success: function (r) {
+                let res = (r && r.result) || {};
+                alert(res.message || (res.sent === true ? $adt.tm_sent : $adt.tm_failed));
             }
         });
     }