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/node/test/cli-security.test.mjs

@@ -18,6 +18,7 @@ async function runCli(args, homeDir) {
         ...process.env,
         HOME: homeDir,
         USERPROFILE: homeDir,
+        XDG_CONFIG_HOME: path.join(homeDir, '.config'),
       },
       stdio: ['ignore', 'pipe', 'pipe'],
     });