## Summary
- drop the dead legacy profile usage metric and active-profile
conversation-start fields
- update role comments so they describe provider and service-tier
preservation without legacy config-profile wording
- pair the code cleanup with the file-backed profile docs update in
openai/developers-website#1476
## Testing
- `just fmt`
- `cargo test -p codex-otel`
- `cargo test -p codex-core` *(fails: existing stack overflow in
`mcp_tool_call::tests::guardian_mode_mcp_denial_returns_rationale_message`)*
- `cargo test -p codex-core --lib
mcp_tool_call::tests::guardian_mode_mcp_denial_returns_rationale_message`
*(fails with the same stack overflow)*
47476e8a8a