feat(orchestrator): harden zero-impact shadow rollout

Gate and bound Portal shadow observations while preserving Native execution. Add fail-closed service boundaries, terminal retention controls, Canary readiness telemetry, ops visibility, and isolated regression coverage.

services/orchestrator/app.mjs

@@ -154,6 +154,28 @@ export function createOrchestratorApp({
     }
   });
 
+  app.delete('/v1/runs/:runId', async (request, response, next) => {
+    try {
+      const result = await runtime.deleteRun(request.params.runId);
+      if (!result) return response.status(404).json({ error: { code: 'RUN_NOT_FOUND' } });
+      return response.json(result);
+    } catch (error) {
+      return next(error);
+    }
+  });
+
+  app.post('/v1/maintenance/purge-terminal-runs', async (request, response, next) => {
+    try {
+      return response.json(await runtime.purgeTerminalRuns({
+        before: request.body?.before,
+        limit: request.body?.limit,
+        dryRun: request.body?.apply !== true,
+      }));
+    } catch (error) {
+      return next(error);
+    }
+  });
+
   app.get('/v1/executor-jobs/:jobId', async (request, response, next) => {
     try {
       const job = await runtime.getExecutorJob(request.params.jobId);