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>

core/Support/helpers/app.php

@@ -487,11 +487,6 @@ function appBuildLayoutNavContext(array $layoutAuth, array $session, array $quer
         $provider = \MintyPHP\App\Module\ModuleClassResolver::resolve($container, $providerClass);
         if ($provider instanceof \MintyPHP\App\Module\Contracts\LayoutContextProvider) {
             $providerData = $provider->provide($session, $container);
-            if (!is_array($providerData)) {
-                throw new \RuntimeException(
-                    "Layout context provider '{$providerClass}' must return an array."
-                );
-            }
             $layoutNav = appMergeLayoutNavProviderData($layoutNav, $providerData, $providerClass);
         }
     }