[codex] Initialize exec-server OpenTelemetry at startup (#25019)

## Summary

- Initialize stderr tracing and the configured OpenTelemetry provider
for local and remote `codex exec-server` startup.
- Instrument the local and remote server entrypoints with a root runtime
span.
- Keep raw Noise environment, registration, and stream identifiers out
of exported spans while preserving them in local debug events.
- Keep telemetry setup in a focused CLI module instead of growing the
top-level command entrypoint.

## Stack

- Previous: none (`#27058` has merged)
- Next: #27466

## Validation

- `just test -p codex-exec-server --lib` (139 passed)
- `just test -p codex-cli --test exec_server` (3 passed)
- `just bazel-lock-check`
- `just fix -p codex-exec-server -p codex-cli`
- `just fmt`

---------

Co-authored-by: Richard Lee <richardlee@openai.com>

codex-rs/cli/tests/exec_server.rs

@@ -1,6 +1,7 @@
 use std::path::Path;
 
 use anyhow::Result;
+use predicates::prelude::PredicateBooleanExt;
 use predicates::str::contains;
 use tempfile::TempDir;
 
@@ -33,3 +34,17 @@ foo = "bar"
 
     Ok(())
 }
+
+#[test]
+fn local_exec_server_ignores_invalid_config_without_strict_config() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    std::fs::write(codex_home.path().join("config.toml"), "not valid toml = [")?;
+
+    let mut cmd = codex_command(codex_home.path())?;
+    cmd.args(["exec-server", "--listen", "stdio"])
+        .assert()
+        .success()
+        .stderr(contains("not valid toml").not());
+
+    Ok(())
+}