feat(server): present Silo identity and close the inherited upstream services

Two coupled changes that must land together, because the same files carry both:
the server now identifies itself as Silo, and every path that would have called
home to a MinIO-operated service is closed.

Product identity
- build-constants.go: store name, UA name and startup banner become Silo. The
  Go identifiers (MinioStoreName, MinioBannerName, ...) keep their names on
  purpose - renaming exported symbols would churn the compatibility surface for
  a cosmetic gain, and the rebrand guard freezes that surface.
- main.go, server-startup-msg.go, ftp-server.go and the user-visible log, help
  and error strings across cmd/ and internal/ switch to Silo. Original MinIO
  copyright, LICENSE, NOTICE and CREDITS are untouched; --version now prints
  the upstream copyright, the pgsty modification notice, and the trademark
  policy's approved "based on MinIO technology" attribution.
- api-headers.go: the HTTP Server header becomes "Silo". This is the one
  externally observable identity change, so TestCommonHeadersUseSiloProductName
  pins it - probes that sniff for "MinIO" must move to capability detection.
- Prometheus metric HELP strings keep their MinIO wording. They are part of the
  metrics contract the guard protects, not product copy.

Configuration directory
- config-dir.go: new installs use ~/.silo. If only ~/.minio exists it is still
  read, with a one-time notice and no files moved. If both exist ~/.silo wins
  and an ambiguity warning is emitted; an explicit --config-dir always wins.
  Covered by TestSelectDefaultConfigDir. The internal .minio.sys layout is
  never renamed - this rule applies to the user config directory only.

Upstream service lockdown
- globalInplaceUpdateDisabled is now true at initialization rather than being
  set from MINIO_UPDATE. common-main.go still parses MINIO_UPDATE so upgrading
  nodes do not fail on an unknown key, but warns that the value is ignored;
  there is no way to re-enable the updater. TestInplaceUpdateCannotBeEnabled
  guards that. Without this, an admin with mc could have overwritten
  /usr/bin/silo with an upstream MinIO binary.
- verifyBinary and commitBinary refuse early; the ServerUpdate v1/v2 admin
  routes and the peer-rest update endpoints stay registered and keep returning
  the existing programmatic error, so clients see a stable failure rather than
  a 404.
- MinioReleaseBaseURL and defaultMinisignPubkey are emptied: no dl.min.io
  download root, and upstream's minisign key is no longer a trust root for
  anything this fork ships.
- cmd/callhome.go is deleted and internal/config/subnet/ is reduced to parsing
  its old keys and reporting that the integration is disabled. config-current.go
  warns instead of failing when callhome or SUBNET settings are present, so an
  upgraded node with those keys still starts.
- internal/config/errors.go replaces the MinIO Slack and support entry points
  with Silo documentation and issue links. Error codes and programmatic fields
  are unchanged.

Verified: the compatibility baseline is unchanged except for the deliberate
removal of the /api/health/upload SUBNET route; go build, go vet and the full
cmd/ and internal/ unit suites pass; a locally built binary starts, serves
S3/Admin/metrics on the unchanged /minio/* routes, answers with Server: Silo,
and falls back to a pre-existing ~/.minio with the expected notice.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

cmd/main.go

@@ -150,16 +150,16 @@ func newApp(name string) *cli.App {
 
 	app := cli.NewApp()
 	app.Name = name
-	app.Author = "MinIO, Inc."
+	app.Author = "Silo contributors"
 	app.Version = ReleaseTag
-	app.Usage = "High Performance Object Storage"
-	app.Description = `Build high performance data infrastructure for machine learning, analytics and application data workloads with MinIO`
+	app.Usage = "S3-compatible object storage"
+	app.Description = `Run independently maintained, S3-compatible object storage with Silo`
 	app.Flags = GlobalFlags
-	app.HideHelpCommand = true // Hide `help, h` command, we already have `minio --help`.
+	app.HideHelpCommand = true // Hide `help, h`; the top-level `silo --help` already covers it.
 	app.Commands = commands
 	app.CustomAppHelpTemplate = minioHelpTemplate
 	app.CommandNotFound = func(ctx *cli.Context, command string) {
-		console.Printf("‘%s’ is not a minio sub-command. See ‘minio --help’.\n", command)
+		console.Printf("‘%s’ is not a %s sub-command. See ‘%s --help’.\n", command, ctx.App.Name, ctx.App.Name)
 		closestCommands := findClosestCommands(command)
 		if len(closestCommands) > 0 {
 			console.Println()
@@ -178,6 +178,7 @@ func newApp(name string) *cli.App {
 func startupBanner(banner io.Writer) {
 	CopyrightYear = strconv.Itoa(time.Now().Year())
 	fmt.Fprintln(banner, color.Blue("Copyright:")+color.Bold(" 2015-%s MinIO, Inc.", CopyrightYear))
+	fmt.Fprintln(banner, color.Blue("Modifications:")+color.Bold(" Copyright 2026 PGSTY contributors"))
 	fmt.Fprintln(banner, color.Blue("License:")+color.Bold(" "+MinioLicense))
 	fmt.Fprintln(banner, color.Blue("Version:")+color.Bold(" %s (%s %s/%s)", ReleaseTag, runtime.Version(), runtime.GOOS, runtime.GOARCH))
 }
@@ -188,6 +189,8 @@ func versionBanner(c *cli.Context) io.Reader {
 	fmt.Fprintln(banner, color.Blue("Runtime:")+color.Bold(" %s %s/%s", runtime.Version(), runtime.GOOS, runtime.GOARCH))
 	fmt.Fprintln(banner, color.Blue("License:")+color.Bold(" GNU AGPLv3 - https://www.gnu.org/licenses/agpl-3.0.html"))
 	fmt.Fprintln(banner, color.Blue("Copyright:")+color.Bold(" 2015-%s MinIO, Inc.", CopyrightYear))
+	fmt.Fprintln(banner, color.Blue("Modifications:")+color.Bold(" Copyright 2026 PGSTY contributors"))
+	fmt.Fprintln(banner, color.Blue("Source compatibility:")+color.Bold(" based on MinIO technology"))
 	return strings.NewReader(banner.String())
 }
 
@@ -197,7 +200,7 @@ func printMinIOVersion(c *cli.Context) {
 
 var debugNoExit = env.Get("_MINIO_DEBUG_NO_EXIT", "") != ""
 
-// Main main for minio server.
+// Main is the Silo server entry point.
 func Main(args []string) {
 	// Set the minio app name.
 	appName := filepath.Base(args[0])