The normalization `replace(/^0+/, '')` over-stripped decimal phase IDs:
`"00.1"` collapsed to `".1"`, while the disk-side extractor yielded
`"0.1"` from `"00.1-<slug>"`. Set membership failed and inserted decimal
phases were silently excluded from every disk scan inside
`buildStateFrontmatter`, causing `state update` to rewind progress
counters.
Strip leading zeros only when followed by a digit
(`replace(/^0+(?=\d)/, '')`), preserving the zero before the decimal
point while keeping existing behavior for zero-padded integer IDs.
Closes#2554
