browser launch schema/MCP missing idle_timeout param

[kiyeonjeon21]

--idle-timeout is implemented in the CLI but not exposed in:

• snact schema browser output
• MCP browser_launch tool parameters

Agents that discover commands via schema or MCP won't know about idle-timeout.

File: crates/snact-cli/src/cmd/schema.rs, crates/snact-cli/src/cmd/mcp.rs