chore: verify boolean values can be parsed as config overrides

[bolinfest]

This is important to ensure that this:

codex --enable unified_exec

and this:

codex --config features.unified_exec=true

are equivalent. Also that when it is passed programmatically:

codex/codex-rs/app-server-protocol/src/protocol/v1.rs

Line 55 in 807e2c2

pub config: Option<HashMap<String, serde_json::Value>>,

then this should work for config:

{"features": {"shell_command_tool": true}}

though I believe also this:

{"features.shell_command_tool": true}