Remove run-summary missing-age self-skip on Waterline dashboard test

Drops the markTestSkipped branch in
V2DashboardStatsControllerTest::testIndexExposesRunSummaryMissingAge.
The workflow rollout-safety contract pair
(operator_metrics.projections.run_summaries.{oldest_missing_run_started_at,max_missing_run_age_ms})
ships in published workflow alpha 2.0.0-alpha.19, which Waterline's
composer install resolves for durable-workflow/workflow: ^2.0@dev.

Each key is now asserted unconditionally with assertArrayHasKey,
matching the matching-role / dispatch-overdue / run-wait / stuck-lease /
ready-due / claim-failed / retrying-activity / dispatch-failed removal
pattern, so a rename or drop of either fails CI loudly instead of
silently self-skipping.

Author: durable-workflow-ops

tests/Feature/V2DashboardStatsControllerTest.php

@@ -912,14 +912,9 @@ public function testIndexExposesRunSummaryMissingAge(): void
         $projections = $response->json('operator_metrics.projections');
         $runSummaries = is_array($projections['run_summaries'] ?? null) ? $projections['run_summaries'] : null;
 
-        if (! is_array($runSummaries)
-            || ! array_key_exists('max_missing_run_age_ms', $runSummaries)
-            || ! array_key_exists('oldest_missing_run_started_at', $runSummaries)) {
-            $this->markTestSkipped(
-                'Vendored workflow package predates the run-summary projection-lag rollout-safety '
-                . 'contract (operator_metrics.projections.run_summaries.{oldest_missing_run_started_at,max_missing_run_age_ms}).',
-            );
-        }
+        $this->assertIsArray($runSummaries);
+        $this->assertArrayHasKey('oldest_missing_run_started_at', $runSummaries);
+        $this->assertArrayHasKey('max_missing_run_age_ms', $runSummaries);
 
         $this->assertTrue(
             $runSummaries['oldest_missing_run_started_at'] === null