Add Minecraft 26.1 Fabric and NeoForge ports

[n1tr0maverick]

Adds Fabric and NeoForge ports for Minecraft 26.1, compiled against the current 26.1.2 hotfix, plus a dedicated-server test harness.

Why

26.1 is still a widely used release line. The 26.2 ports already landed; this adds matching 26.1 / 26.1.2 jars so players on that version can use the mod without upgrading Minecraft.

Loaders

• fabric/26.1 — Fabric Loader 0.19.3, Fabric API 0.155.2+26.1.2, Minecraft ~26.1, Java 25
• neoforge/26.1 — NeoForge 26.1.2.97, Minecraft [26.1,26.2), Java 25

Mod version string: 3.8-26.1.

26.1 vs 26.2

The ports are based on the 26.2 sources, with 26.1 API differences applied:

• Toasts use Minecraft.getToastManager() (26.2 moved this onto Gui)
• Official mappings, Identifier, GuiGraphicsExtractor toast rendering, Fabric PayloadTypeRegistry.clientboundPlay() / serverboundPlay(), NeoForge client payload registration

Minecraft harness

scripts/minecraft-harness/run_harness.py boots a headless dedicated server, runs /backup start over RCON, and asserts a zip backup is written.

python3 scripts/minecraft-harness/run_harness.py --loader fabric --mc 26.1
python3 scripts/minecraft-harness/run_harness.py --loader neoforge --mc 26.1
python3 scripts/minecraft-harness/run_harness.py --loader fabric --mc 26.2
python3 scripts/minecraft-harness/run_harness.py --loader neoforge --mc 26.2

There is also a workflow_dispatch GitHub Action: Minecraft harness.

Verification

Local compileJava + build succeeded for both 26.1 loaders.

Live dedicated-server harness passed:

Loader	Result
Fabric 26.1	PASS — backup_2026-08-25_10-07-32.zip (163 KB)
NeoForge 26.1	PASS — backup_2026-08-25_10-08-12.zip (165 KB)
Fabric 26.2	PASS — backup_2026-08-25_10-32-36.zip (9 KB)
NeoForge 26.2	PASS — backup_2026-08-25_10-36-27.zip (169 KB)

All four runs loaded the mod (Config loaded!!), accepted backup start over RCON, and wrote a zip before stop.