refactor: split RunnerTests into focused files
Merged
TH
8mo ago+1974+1974+0123456789012345678901234567890123456789-1901-1901-0123456789012345678901234567890123456789
Summary
Split the large iOS runner UI test harness into focused RunnerTests+*.swift files, extracted wire models and environment helpers, and kept RunnerTests.swift as the test entry/state surface.
Touched files: 11
Scope: stayed within the iOS runner UITest module and ios-runner/README.md.
Validation
pnpm build:xcuitest