v0.23.0

Added

• Performance testing: start measuring "name" ... stop measuring measures, over those steps, the app's memory and frame timings (agent 0.23+, every device), its CPU (Android via /proc, iOS simulator via host ps; not a physical iPhone) and its HTTP traffic. Assertions: see memory below N MB, see memory growth below N MB, see cpu below N percent, see cpu peak below N percent, see slow frames below N percent, see frame time below N ms, see slowest frame below N ms, see data transferred below N KB, and see response <ref> below N ms. EBNF + conformance tests.
• Baselines and trends: probe test --perf-baseline FILE fails a test whose numbers got worse than the baseline by the tolerance (--perf-tolerance, default 20%, with noise floors); --perf-update-baseline writes it; every run appends to reports/perf-history.jsonl; probe perf trend and probe perf compare.
• Reports: a perf array per test in the JSON report, a Performance block in the HTML report, measurements under each result in Probe Studio.
• MCP: tools perf_trend and perf_compare; the guide covers performance, backend data, waiting, localization and the new flags.
• New guide "Performance testing"; proposal for the unified Studio UI (docs/proposals/performance-testing.md).