AtlasSpigot 1.21.8 - v1 (new Leaf version track)

A fourth Leaf version track: Minecraft 1.21.8 - same rebrand, same bStats service wiring, same tuning philosophy as 26.2, 26.1.2, and 1.21.11.

Real finding this time, caught by checking the actual generated config rather than assuming parity with the newer tracks: this branch's Leaf source is missing RegionFormatConfig entirely - no B_LINEAR region format support exists here, so world storage stays on vanilla MCA. Its ReduceUselessPackets module is also slimmer - only reduce-entity-move-packets exists; reduce-entity-motion-packets and disable-useless-particles aren't present in this version. Both are documented in 1.21.8/NOTES.md - applied only what's actually real for this version rather than writing config keys that silently wouldn't exist.

entity-tracking-range is halved from this version's own stock defaults (same 128/96/96/96/128/64 baseline as the other recent tracks).

Verified: booted fresh with no config to capture real defaults, then booted again with the full tuned config applied - clean both times, correct AtlasSpigot branding, no errors, no experimental-module warnings.

Config, notes, source-patches, and jar live under 1.21.8/.