Volume encryption follows the filer: weed s3, weed-vector, weed-worker, weed-vector-cli (#12487)

* s3: encrypt volume data when the filer is configured to

weed s3 read the filer's configuration at startup (buckets dir, filer
group, masters, metrics, maxMB) but not its -encryptVolumeData, so a
cluster that turned encryption on at the filer still had S3 uploads
stored plain, while uploads through the filer itself were encrypted.
The gateway now encrypts when either its own -encryptVolumeData or the
filer's is set; weed-vector, weed-worker and weed-vector-cli already
follow the filer's.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011UpvafvK8JpagF94MHWqwK

* vector: weed-vector, weed-worker and the CLI take volume encryption from the filer

They already encrypted chunks for the volume servers when the filer's
configuration said so, or when their own --encryptVolumeData did. With
weed s3 following the filer too, the filer's -encryptVolumeData is the
one switch for every writer, so the three flags are removed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011UpvafvK8JpagF94MHWqwK

* S3 Vectors tests: turn volume encryption on at the filer

VECTOR_ENCRYPT_VOLUMES=1 set -encryptVolumeData on the gateway, the
engine and the worker. It now sets it on the filer alone, so the leg
checks that each of them follows the filer: the gateway's stored chunks
carry a cipher key (with a gateway that ignores the filer, the leg fails
on "the gateway stored a chunk without a cipher key"), and so do the
engine's.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011UpvafvK8JpagF94MHWqwK

* weed-worker README: volume encryption follows the filer

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011UpvafvK8JpagF94MHWqwK

* s3: help text says the filer's -encryptVolumeData turns S3 encryption on

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* S3 Vectors tests: plain legs check the engine stored no cipher key

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

weed/command/server.go

@@ -201,7 +201,7 @@ func init() {
 	s3Options.concurrentFileUploadLimit = cmdServer.Flag.Int("s3.concurrentFileUploadLimit", 0, "limit number of concurrent file uploads for S3, 0 means unlimited")
 	s3Options.enableIam = cmdServer.Flag.Bool("s3.iam", true, "enable embedded IAM API on the same S3 port")
 	s3Options.iamReadOnly = cmdServer.Flag.Bool("s3.iam.readOnly", true, "disable IAM write operations on this server")
-	s3Options.cipher = cmdServer.Flag.Bool("s3.encryptVolumeData", false, "encrypt data on volume servers for S3 uploads")
+	s3Options.cipher = cmdServer.Flag.Bool("s3.encryptVolumeData", false, "encrypt data on volume servers for S3 uploads; on whenever -filer.encryptVolumeData is")
 	s3Options.externalUrl = cmdServer.Flag.String("s3.externalUrl", "", "the external URL clients use to connect (e.g. https://api.example.com:9000). Advertised to Iceberg and Lance clients, and tried first when verifying S3 signatures behind a reverse proxy. Falls back to S3_EXTERNAL_URL env var.")
 	s3Options.allowBackslashInKey = cmdServer.Flag.Bool("s3.allowBackslashInKey", false, allowBackslashInKeyUsage)
 	s3Options.defaultFileMode = cmdServer.Flag.String("s3.defaultFileMode", "", "default file mode for S3 uploaded objects, e.g. 0660, 0644, 0666")