refactor: fix all 105 PHPStan 2 strict type findings across core and modules

Resolve all non-false-positive PHPStan 2 findings, reducing the baseline
from 486 to 382 entries (only unused-public false positives remain).

Categories fixed:
- Remove 39 redundant type checks (is_string, is_array, is_object, method_exists)
- Remove 12 no-op array_values() on already-sequential lists
- Simplify 13 null-coalesce on guaranteed offsets
- Remove 8 always-true instanceof checks
- Replace 12 redundant test assertions (assertTrue(true) → addToAssertionCount)
- Simplify 6 unnecessary nullsafe operators (?-> → ->)
- Fix 6 always-true !== '' comparisons
- Fix remaining: unset.offset, return.unusedType, staticMethod narrowing

53 files changed across core/, modules/, pages/, and tests/.

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

modules/helpdesk/lib/Module/Helpdesk/Service/TicketCommunicationService.php

@@ -193,9 +193,6 @@ class TicketCommunicationService
         // Collect support user name → ticket code mappings
         $supportUserNamesByTicket = [];
         foreach ($tickets as $ticket) {
-            if (!is_array($ticket)) {
-                continue;
-            }
             $no = trim((string) ($ticket['No'] ?? ''));
             $name = trim((string) ($ticket['Support_User_Name'] ?? ''));
             if ($no !== '' && $name !== '') {
@@ -784,7 +781,7 @@ class TicketCommunicationService
         }
 
         if (preg_match('/^(\d{2}:\d{2})(:\d{2})?/', $time, $m) === 1) {
-            return isset($m[2]) && $m[2] !== '' ? ($m[1] . $m[2]) : ($m[1] . ':00');
+            return isset($m[2]) ? ($m[1] . $m[2]) : ($m[1] . ':00');
         }
 
         return $time;
@@ -902,9 +899,6 @@ class TicketCommunicationService
 
         $nameMap = [];
         foreach ($contacts as $contact) {
-            if (!is_array($contact)) {
-                continue;
-            }
             $contactNo = strtoupper(trim((string) ($contact['No'] ?? '')));
             $contactName = trim((string) ($contact['Name'] ?? ''));
             if ($contactNo === '' || $contactName === '') {
@@ -1075,7 +1069,7 @@ class TicketCommunicationService
             }
         }
 
-        return $trimmed !== '' ? $trimmed : '';
+        return $trimmed;
     }
 
     private function normalizeActorRole(string $createdByType, string $actor): string