Stabilize provider compatibility integration verification

Keep integrated G008 provider changes formatted and compile-ready so worker follow-up commits can merge against a clean leader baseline.

Constraint: G008 provider verification must pass before ultragoal checkpointing.
Confidence: high
Scope-risk: narrow
Directive: Keep provider compatibility follow-ups rebased on this formatted baseline before retrying failed cherry-picks.
Tested: cargo test --manifest-path rust/Cargo.toml -p api providers:: -- --nocapture; cargo test --manifest-path rust/Cargo.toml -p api --test openai_compat_integration -- --nocapture --test-threads=1
Not-tested: full workspace clippy; known pre-existing runtime policy_engine LaneContext clippy warning remains outside this change.

Co-authored-by: OmX <omx@oh-my-codex.dev>

rust/crates/api/src/providers/openai_compat.rs

@@ -1608,6 +1608,7 @@ mod tests {
         ToolChoice, ToolDefinition, ToolResultContentBlock,
     };
     use serde_json::json;
+    use std::collections::BTreeMap;
     use std::sync::{Mutex, OnceLock};
 
     #[test]