feat(cli): forward env-driven cluster driver to the runtime in os serve (#2226)

`os serve` constructed the Runtime without a cluster config, so it always used
the in-memory cluster driver — a multi-replica deployment could not coordinate
(and the split-brain guard blocked it). `os serve` now reads OS_CLUSTER_DRIVER
(+ OS_REDIS_URL), dynamically imports the matching remote driver package (so it
works in both config-boot and compiled-artifact mode), and forwards the cluster
config to the Runtime. Open-core ships only the in-memory driver; remote drivers
(e.g. @objectstack/service-cluster-redis) are provided by the EE distribution —
absent ⇒ graceful fallback to in-memory.

Verified via A/B boot (local redis): with OS_CLUSTER_DRIVER=redis + replicas=2
the server boots (guard passes = redis active); without it, replicas=2 trips the
split-brain guard (memory). Enables the EE multi-node activation (cloud ADR-0018)
of the cache-invalidation (#2213) and scheduler-leader-election (#2219) seams.

Co-authored-by: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: 3 people

packages/cli/src/commands/serve.ts

@@ -531,10 +531,23 @@ export default class Serve extends Command {
         }),
       };
 
+      // Cluster wiring: env-driven driver selection (mirrors OS_DATABASE_URL).
+      // The remote driver self-registers on import; import it dynamically so it
+      // works in BOTH config-boot and compiled-artifact mode. Open-core ships
+      // only the in-memory driver — remote drivers (e.g. redis) come from the EE
+      // distribution; if absent we fall back to the in-memory cluster.
+      let clusterConfig: { driver: string; url?: string } | undefined;
+      const __clusterDriver = process.env.OS_CLUSTER_DRIVER?.trim();
+      if (__clusterDriver && __clusterDriver !== 'memory') {
+        try { await import(`@objectstack/service-cluster-${__clusterDriver}`); }
+        catch { /* may already be registered by the loaded config */ }
+        clusterConfig = { driver: __clusterDriver, url: process.env.OS_REDIS_URL };
+      }
       const runtime = new Runtime({
         kernel: {
             logger: loggerConfig
-        }
+        },
+        cluster: clusterConfig as any,
       });
       const kernel = runtime.getKernel();