Refactoring:
- Extract stateReplaceFieldWithFallback() to state.cjs as single source of truth
for the try-primary-then-fallback pattern that was duplicated inline across
phase.cjs, milestone.cjs, and state.cjs
- Replace all inline bold-only regex patterns in cmdPhaseComplete with shared
stateReplaceField/stateExtractField helpers — now supports both **Bold:**
and plain Field: STATE.md formats (fixes the same bug as #924)
- Replace inline bold-only regex patterns in cmdMilestoneComplete with shared helpers
- Replace inline bold-only regex for Completed Phases/Total Phases/Progress
counters in cmdPhaseComplete with stateExtractField/stateReplaceField
- Replace inline bold-only Total Phases regex in cmdPhaseRemove with shared helpers
Security:
- Fix command injection surface in isGitIgnored (core.cjs): replace execSync with
string concatenation with execFileSync using array arguments — prevents shell
interpretation of special characters in file paths
Tests (7 new):
- 5 tests for stateReplaceFieldWithFallback: primary field, fallback, neither,
preference, and plain format
- 1 regression test: phase complete with plain-format STATE.md fields
- 1 regression test: milestone complete with plain-format STATE.md fields
854 tests pass (was 847). No behavioral regressions.