add --dangerously-bypass-hook-trust CLI flag (#21768)

# Why

Hook trust happens through the TUI in `/hooks` so it can block
non-interactive use cases. This flag will allow users that are using
codex headlessly to bypass hooks when they want to.

# What

This adds one invocation-scoped escape hatch.

- the CLI flag sets a runtime-only `bypass_hook_trust` override; there
is no durable `config.toml` setting
- hook discovery still respects normal enablement, so explicitly
disabled hooks remain disabled
- we show a `--dangerously-bypass-hook-trust is enabled. Enabled hooks
may run without review for this invocation.` message on startup so
accidental use is visible in both interactive and exec flows

This keeps “enabled” and “trusted” as separate concepts in the normal
path, while giving CI/E2E callers a stable way to opt into the
exceptional path when they already control the hook set.

codex-rs/thread-manager-sample/src/main.rs

@@ -163,6 +163,7 @@ fn new_config(model: Option<String>, arg0_paths: Arg0DispatchPaths) -> anyhow::R
     let mut config = Config {
         config_layer_stack: ConfigLayerStack::default(),
         startup_warnings: Vec::new(),
+        bypass_hook_trust: false,
         model,
         service_tier: None,
         review_model: None,