test(01-02): add phase utility, string helper, and roadmap tests
- escapeRegex: special chars, empty string, plain string
- generateSlugInternal: kebab-case, special chars, null/empty
- normalizePhaseName: padding, letters, decimals, multi-level
- comparePhaseNum: numeric sort, letters, decimals, equality
- safeReadFile: existing file, missing file
- pathExistsInternal: existing, non-existing, absolute paths
- getMilestoneInfo: version extraction, defaults
- searchPhaseInDir: finding dirs, plans/summaries, incomplete,
research/context detection, slug generation
- findPhaseInternal: current phases, archived milestones, null
- getRoadmapPhaseInternal: export exists (REG-02), goal extraction,
colon-outside-bold format, missing roadmap, section text
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