Move trusted skill evidence into the Guardian context registry (#43599)

## What changed

Move trusted skill rendering into `codex-guardian-context` as `TrustedSkills` and collect it through an async-only context section. Pass the collected section to the sampler, preserving the separate developer message and bounded JSON rendering. Omit skill paths from `Debug` output, exposing only their count.

## Testing

Move rendering tests alongside the shared type, covering multiple paths and escaped UTF-8 within the size budget. Extend registry tests to cover async-only inclusion, omission for empty input, section ordering, and path redaction in debug output.

GitOrigin-RevId: c0778067f19d31e693ca954aee1a7d7be8f9739a

codex-rs/core/src/guardian/prompt.rs

@@ -248,7 +248,9 @@ pub(crate) async fn build_guardian_prompt_items_with_parent_turn(
                     push_text(text);
                 }
             }
-            ContextSection::PreviousReviews(_) | ContextSection::TrustedTool(_) => {
+            ContextSection::PreviousReviews(_)
+            | ContextSection::TrustedTool(_)
+            | ContextSection::TrustedSkills(_) => {
                 unreachable!("trusted review and tool sections are async-only")
             }
             ContextSection::ConversationTranscript { .. } => {}
@@ -485,6 +487,7 @@ pub(super) fn collect_guardian_context(
         permissions,
         previous_reviews: None,
         trusted_tool: None,
+        trusted_skill_paths: &[],
     })
 }