AtlasSpigot 26.1.2 - v1 (new Leaf version track)

A second Leaf version track: Minecraft 26.1.2, alongside the existing 26.2 and 1.21.11 tracks - same rebrand, same bStats service wiring (reports to the same registered project), same tuning philosophy.

Verified against this branch's actual applied source before assuming anything carried over: same I_GLOBAL_CONFIG_FILE naming convention and Metrics.java layout as the 1.21.11 track, so those source-patches diffs apply here unchanged - confirmed by spot-checking line numbers first, not copied blind.

entity-tracking-range is halved from this version's own stock defaults (128/96/96/96/128/64, same stock baseline as 1.21.11's) rather than reused from another track - documented inline in 26.1.2/spigot.yml.

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

Config, source-patches, and jar for this track live under 26.1.2/. Full multi-version, multi-fork roadmap now tracked in ROADMAP.md.