test(cluster,server): gated object-storage cluster e2e + CI wiring + docs

s3_cluster.rs runs the full control-plane lifecycle against a real
bucket (CI: containerized RustFS; locally the RustFS binary): import →
lock released (pins the drop-time release regression caught on the first
live smoke) → apply (graph roots + catalog on the bucket, nothing local)
→ serving snapshots from both the config dir and the bare URI → schema
evolution → approved delete (prefix removal) → empty-cluster refusal.
The server suite gains the config-free boot test: --cluster s3://… with
zero local files serves a stored query over HTTP.

CI: the rustfs job runs both suites; the classify filter covers the
cluster store/serve modules and the new test files. The server smoke
drops its name filter — every test in the s3 target is bucket-gated, and
a filter matching nothing passes vacuously (which silently ran zero
tests for a while).

Docs: deployment.md gains the Bucket-no-volume shape as the preferred
cloud deployment; cluster.md/server.md document --cluster <uri>;
testing.md maps the new suite.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/user/deployment.md

@@ -47,10 +47,31 @@ omnigraph-server s3://my-bucket/graphs/example/releases/2026-04-10-v0.1.0 \
 
 ## Cluster Mode in Containers (AWS, Railway)
 
-A cluster-booted deployment serves a **cluster directory** (config + state
-ledger + content-addressed catalog + graph data) from a mounted volume — the
-one structural difference from the stateless S3 single-graph shape, which
-needs no volume at all. The container contract:
+A cluster-booted deployment has **two shapes** since the `storage:` root
+(RFC-006):
+
+- **Bucket, no volume (preferred for cloud)** — the cluster's ledger,
+  catalog, and graph data live under an object-storage root
+  (`storage: s3://bucket/prefix` in `cluster.yaml`). The server boots
+  **config-free** from the bare URI; the container needs no volume at all:
+
+  ```bash
+  docker run -d \
+    -e OMNIGRAPH_CLUSTER=s3://my-bucket/clusters/company-brain \
+    -e AWS_ACCESS_KEY_ID=... -e AWS_SECRET_ACCESS_KEY=... \
+    -e OMNIGRAPH_SERVER_BEARER_TOKEN=... \
+    -p 8080:8080 <image>
+  ```
+
+  Day-2 runs from any operator checkout of the config repo:
+  `omnigraph cluster apply --config ./company-brain` (the `storage:` key
+  routes every stored byte to the bucket), then restart the service. The
+  state lock is genuinely cross-machine on object storage, so CI and
+  operator shells contend safely.
+
+- **Volume (file-rooted)** — the original shape: the whole cluster
+  directory on a mounted volume. Still fully supported; the container
+  contract:
 
 ```bash
 docker run -d \
@@ -102,8 +123,6 @@ above).
 
 ### Constraints (current honest list)
 
-- **Cluster directories are local-filesystem** — the volume is mandatory;
-  S3-hosted cluster dirs are not supported.
 - **No hot reload** — applied changes serve on the next restart.
 - **Single-writer apply** — run `cluster apply` from one place at a time
   (the state lock enforces this; CI or one operator shell, not both).