Route MCP tool calls through shared approval handling (#38108)

## What changed

- Represent MCP tool calls as approval actions and route them through the
  session-level approval flow for permission hooks, reviewer selection,
  rejection handling, and resolution telemetry.
- Preserve MCP-specific user prompts, session and persistent approval choices,
  and the approval policy and reviewer captured for the tool call.

## Testing

- Add coverage for permission hooks resolving MCP calls before user or
  automatic review, persistence choices, captured policy routing, and MCP turn
  metadata with strict automatic review enabled.

GitOrigin-RevId: 8e134b3d17a19dc62b3b56076d2cd05a54c9f638

codex-rs/core/src/tools/mod.rs

@@ -21,6 +21,7 @@ mod tool_namespaces_info;
 use std::borrow::Cow;
 
 use crate::session::turn_context::TurnContext;
+pub(crate) use approvals::ApprovalContext;
 use codex_features::Feature;
 use codex_protocol::exec_output::ExecToolCallOutput;
 use codex_protocol::openai_models::ToolMode;