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/audit/lib/Module/Audit/Repository/UserLifecycleAuditRepository.php

@@ -65,17 +65,17 @@ class UserLifecycleAuditRepository
         $actions = RepoQuery::normalizeStringList(
             $filters['actions'] ?? '',
             self::FILTER_OPTIONS_LIMIT_MAX,
-            static fn (string $value): string => UserLifecycleAction::tryNormalize($value)?->value ?? ''
+            static fn (string $value): string => UserLifecycleAction::tryNormalize($value)->value ?? ''
         );
         $statuses = RepoQuery::normalizeStringList(
             $filters['statuses'] ?? '',
             self::FILTER_OPTIONS_LIMIT_MAX,
-            static fn (string $value): string => UserLifecycleStatus::tryNormalize($value)?->value ?? ''
+            static fn (string $value): string => UserLifecycleStatus::tryNormalize($value)->value ?? ''
         );
         $triggerTypes = RepoQuery::normalizeStringList(
             $filters['trigger_types'] ?? '',
             self::FILTER_OPTIONS_LIMIT_MAX,
-            static fn (string $value): string => UserLifecycleTriggerType::tryNormalize($value)?->value ?? ''
+            static fn (string $value): string => UserLifecycleTriggerType::tryNormalize($value)->value ?? ''
         );
         $actorUserIds = array_slice(
             RepoQuery::normalizeIdList($filters['actor_user_ids'] ?? ''),

modules/audit/lib/Module/Audit/Service/FrontendTelemetryIngestService.php

@@ -485,11 +485,7 @@ class FrontendTelemetryIngestService
 
         $cutoff = $now - self::DEDUPE_WINDOW_SECONDS;
         foreach ($seen as $key => $timestamp) {
-            if (!is_string($key)) {
-                unset($seen[$key]);
-                continue;
-            }
-            if (!is_int($timestamp) || $timestamp < $cutoff) {
+            if ($timestamp < $cutoff) {
                 unset($seen[$key]);
             }
         }

modules/audit/pages/audit/frontend-telemetry/ingest().php

@@ -28,18 +28,10 @@ if (!Session::checkCsrfToken()) {
 }
 
 $body = requestInput()->bodyAll();
-if (!is_array($body)) {
-    http_response_code(204);
-    return;
-}
 
 $allowedKeys = ['event_type', 'severity', 'message', 'fingerprint', 'meta', 'occurred_at'];
 $csrfKey = Session::$csrfSessionKey;
 foreach ($body as $key => $value) {
-    if (!is_string($key)) {
-        continue;
-    }
-
     if ($key === $csrfKey) {
         continue;
     }