Add criterion benchmarks for MCP tool latency

[louis030195]

Context

Need to measure and track latency for MCP tools and SDK functions.

Current state

• windows_benchmarks.rs: Window tree building, UI automation latency
• unified_latency_benchmark.rs: Input event capture latency

Missing

MCP tool-level benchmarks

Proposed

Add crates/terminator-mcp-agent/benches/:

• tool_latency.rs: MCP tool benchmarks (criterion)
• transpiler_bench.rs: TS transpilation benchmarks

Metrics to measure

Tool	Metrics
execute_browser_script	Transpile time (TS vs JS), extension roundtrip
run_command	Engine startup (bun vs node vs python)
get_window_tree	Tree size vs latency
click/type_text	Locator resolution + action

Why Rust/criterion

• Statistical rigor (percentiles, regression detection)
• HTML reports
• CI integration
• Single source of truth for all SDKs