Remote startup timing accepts numbers supplied by the runner

On remote runs, startup phase timing can merge a JSON blob from the CCR_RUNNER_STARTUP_TIMING environment variable into the reported figures, validating each field for type, range and pattern: names must be lowercase with underscores, and numbers and phase durations are capped. Prewarm, prefetch and delta-reset values from the environment are reported alongside. Nothing is reported unless CLAUDE_CODE_REMOTE is set.