fix: pass MCP tool timeout from metadata

[zerone0x]

Summary

Fixes #308

Allows ACP client-provided MCP servers to set Codex's tool_timeout_sec via MCP server _meta metadata (tool_timeout_sec or toolTimeoutSec).

Changes

• Reads tool_timeout_sec metadata from HTTP and stdio MCP server configs
• Passes the parsed timeout through to Codex McpServerConfig
• Adds unit coverage for numeric, string, and invalid timeout metadata

Verification

• cargo fmt --check
• git diff --check
• cargo test mcp_tool_timeout_sec --lib (blocked: local environment has no C linker, cc not found)

[benbrandt]

Hi thanks for taking the time to dig in!
Development is moving to agentclientprotocol/codex-acp. The new adapter is built on the new Codex App Server, and we are pooling implementation and maintenance work across teams there. If this is still needed, please open a PR for that one. Thanks!