feat(core): endpointUrl() helper — query-safe URLs for module routes

Introduce a helper that returns the registered route TARGET for a given
source path, so URLs built for endpoints that carry query parameters do
not rely on MintyPHP's applyRoutes() rewrite layer — that layer compares
the full request URI (including `?query`) against source paths and
silently misses modules where path ≠ target.

- core/Support/helpers/app.php: endpointUrl($path) consults
  ModuleRegistry::getRoutes(), returns lurl(target) when the path is a
  registered module source path, otherwise falls through to lurl($path).
  Safe fallback when the container or registry is unavailable.
- modules/audit/pages/audit/system-audit/index(default).phtml: replace
  the ad-hoc target-path workaround with endpointUrl('admin/system-audit/
  export'). Callers can now write the natural source path without
  knowing about the rewrite trap.
- Apply the same helper to modules/helpdesk/.../domains/index and
  pages/admin/users/index for consistency — a no-op where path already
  equals target, but establishes the convention: every export/data
  endpoint URL in page configs goes through endpointUrl().
- tests/Support/Helpers/EndpointUrlTest: 5 cases covering source→target
  resolution, idempotence when path == target, fall-through for
  unregistered paths, leading-slash normalization, and graceful
  degradation when the registry is missing. Uses
  AppContainerIsolationTrait per the contract test in
  tests/Architecture/AppContainerIsolationContractTest.

Gates: PHPUnit 1894 OK, PHPStan 0 errors, module:sync ok.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Support/Helpers/EndpointUrlTest.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace MintyPHP\Tests\Support\Helpers;
+
+use MintyPHP\App\AppContainer;
+use MintyPHP\App\Module\ModuleRegistry;
+use MintyPHP\Tests\Support\AppContainerIsolationTrait;
+use PHPUnit\Framework\TestCase;
+
+class EndpointUrlTest extends TestCase
+{
+    use AppContainerIsolationTrait;
+
+    protected function tearDown(): void
+    {
+        $this->restoreAppContainer();
+    }
+
+    public function testResolvesSourcePathToTarget(): void
+    {
+        $this->installRegistryWithRoutes([
+            ['path' => 'admin/system-audit/export', 'target' => 'audit/system-audit/export', 'module_id' => 'audit'],
+        ]);
+
+        $this->assertStringEndsWith('audit/system-audit/export', endpointUrl('admin/system-audit/export'));
+    }
+
+    public function testIdempotentWhenPathEqualsTarget(): void
+    {
+        $this->installRegistryWithRoutes([
+            ['path' => 'helpdesk/domains/export', 'target' => 'helpdesk/domains/export', 'module_id' => 'helpdesk'],
+        ]);
+
+        $this->assertStringEndsWith('helpdesk/domains/export', endpointUrl('helpdesk/domains/export'));
+    }
+
+    public function testFallsThroughToLurlForUnregisteredPath(): void
+    {
+        $this->installRegistryWithRoutes([]);
+
+        $this->assertSame(lurl('admin/users/export'), endpointUrl('admin/users/export'));
+    }
+
+    public function testIgnoresLeadingSlash(): void
+    {
+        $this->installRegistryWithRoutes([
+            ['path' => 'admin/system-audit/export', 'target' => 'audit/system-audit/export', 'module_id' => 'audit'],
+        ]);
+
+        $this->assertSame(
+            endpointUrl('admin/system-audit/export'),
+            endpointUrl('/admin/system-audit/export')
+        );
+    }
+
+    public function testDegradesGracefullyWhenRegistryMissing(): void
+    {
+        $this->pushAppContainer(new AppContainer());
+
+        // No ModuleRegistry registered — endpointUrl() must fall back, not throw.
+        $this->assertSame(lurl('some/path'), endpointUrl('some/path'));
+    }
+
+    /**
+     * @param list<array{path: string, target: string, module_id?: string}> $routes
+     */
+    private function installRegistryWithRoutes(array $routes): void
+    {
+        // ModuleRegistry is final and has no public constructor — build via
+        // reflection and write the merged-routes field directly. Only used
+        // by endpointUrl() via getRoutes(), so that is all we need to stage.
+        $registry = (new \ReflectionClass(ModuleRegistry::class))->newInstanceWithoutConstructor();
+        $routesProp = (new \ReflectionClass(ModuleRegistry::class))->getProperty('mergedRoutes');
+        $routesProp->setValue($registry, $routes);
+
+        $container = new AppContainer();
+        $container->set(ModuleRegistry::class, static fn (): ModuleRegistry => $registry);
+        $this->pushAppContainer($container);
+    }
+}