Renames the combined E2E test to match the new skill split:
- checkpoint-save-resume → context-save-writes-file
Extracts the Save flow from context-save/SKILL.md, asserts a file
gets written with valid YAML frontmatter.
- New: context-restore-loads-latest
Seeds two saved-context files with different YYYYMMDD-HHMMSS
prefixes AND scrambled filesystem mtimes (so mtime DISAGREES with
filename order). Hand-feeds the restore flow and asserts the newer-
by-filename file is loaded. Locks in the "newest by filename prefix,
not mtime" guarantee.
touchfiles.ts: old 'checkpoint-save-resume' key removed from both
E2E_TOUCHFILES and E2E_TIERS maps; new keys added to both. Leaving a
key in one map but not the other silently breaks test selection.
Golden baselines (claude/codex/factory ship skill) regenerated to match
the new preamble routing rules from the previous commit.
daaec21c2c