Preserve complete actions in Guardian approval reviews (#44569)

## Why

Truncating action arguments can leave approval reviewers evaluating incomplete actions. Large actions need complete review input and explicit handling when they exceed the review budget.

## What changed

- Remove action truncation and the fixed synchronous action byte limit. Admit complete actions against the whole-request budget, splitting long text losslessly into bounded transport parts and accounting for their framing.
- Route actions exceeding the asynchronous action budget to synchronous review. Prevent cached scores from covering oversized calls, including expanded approval arguments, while allowing later small actions to recover score reuse.
- Request user approval when optional review exhausts its local input budget. Keep required review and compaction service failures closed to approval, and retire exhausted review sessions.

## Testing

Add coverage for complete large-action delivery, optional user fallback, required-review denial, subsequent review recovery, async overflow through MCP approval routing, and lossless text splitting with budget accounting.

GitOrigin-RevId: 08f06e68a94b2f779480dd6b6cf5bc30b241f6dd

codex-rs/core/src/session/turn.rs

@@ -333,6 +333,9 @@ pub(crate) async fn run_turn(
         }
         // Incoming evidence can overflow even below the normal history
         // threshold. Keep it pending while compacting, then select once more.
+        sess.services
+            .thread_extension_data
+            .insert(crate::guardian::ExhaustedReviewBudget::Compacting);
         run_auto_compact(
             &sess,
             Arc::clone(&first_step_context),
@@ -704,6 +707,9 @@ pub(crate) async fn run_turn(
                 // token-budget resets must fail closed and retire the reviewer.
                 // Retry once per model step, so ineffective compaction cannot loop.
                 guardian_budget_compacted = true;
+                sess.services
+                    .thread_extension_data
+                    .insert(crate::guardian::ExhaustedReviewBudget::Compacting);
                 run_auto_compact(
                     &sess,
                     Arc::clone(&step_context),