#41: re-partition the RU-ARK mainland's 28-part lat>=68 Arctic-coast band
into two new regions via a new turf-free, idempotent pipeline stage
scripts/split-arkhangel-band.mjs (npm run split:regions:band), mirroring the
#31 split:
- RU-PEO (Pechora, 13 parts, ~37,678 km2) -> key pechora-qwhs
- RU-YAM (Yamal, 15 parts, ~51,722 km2) -> key yamal-gosw
- RU-ARK keeps its id/name/key arkhangel-sk-lhbk (ownership-safe); the 5-part
lat<68 core (~305,229 km2) stays RU-ARK.
Pure re-partition: no geometry moved (byte-identical union). The two new
features are inserted immediately after RU-ARK-SZ. Manifests regenerated with
the real scripts (1,798 -> 1,800 keys + adjacency; adjacency pairs 4,471 ->
4,473). Fixed-point dataset unchanged except feature count (11,794 parts /
11,795 rings / 164,801 verts / 1 KZ-KZY hole). Four dataset/manifest tests
updated (RUS 82 -> 84 sub-regions). Version 0.25.0 -> 0.26.0.
Fixes#41
Deterministic <name-slug>-<4char> key per sub-region: name via NFKD strip +
fold table (ə ø ð đ œ ł) + a-z0-9 collapse; 4-char from FNV-1a of the stable
feature id, salted on within-slug collision so all 1,796 keys are unique.
Builtins only (no @turf). Idempotent (byte-identical on re-run).