chore(oss): audit the server package and resync the SDK mirrors

Split the 657-line operation service into eor, submit, and verify
modules, add the AGENT_REVOKED and KEY_RETIRED codes the Backend already
emits, and condense every multi-line comment. Mirror Node, Python, and
Go at 2.1.0 with the deep-health 503, non-idempotent retry, rotation
grace, and path-encoding fixes. Document which routes and response
fields the self-hosted server does not provide.

Claude-Session: https://claude.ai/code/session_01Agoc9bRVE9KL7mmWtey9Vq

sdks/go/cmd/elydora/cli_secrets.go

@@ -119,9 +119,6 @@ func readSecretFileWithOpen(
 	if err := validateSecretFile(before, path, label); err != nil {
 		return "", err
 	}
-	if !os.SameFile(before, before) {
-		return "", fmt.Errorf("establish %s file identity at %s", label, path)
-	}
 
 	file, err := openFile(path)
 	if err != nil {