Fix Forge 1.12 packaged access transformer

[SkyBlade1978]

Summary

• declare the Forge 1.12 access transformer in the published jar manifest
• bump this target to 4.0.7.112021
• verify the actual reobfuscated jar contains and advertises both required transformer rules
• add a reusable packaged Forge fresh/reload gate and extend runtime log scanning to captured launcher output

Root cause

The 4.0.6 jar contained META-INF/accesstransformer.cfg, but its manifest did not contain FMLAT: accesstransformer.cfg. ForgeGradle development launches supplied the transformer separately, so automated development tests passed while normal CurseForge/packaged launches failed with IllegalAccessError when the first world loaded.

Validation

• 144 tests across 36 suites, with no failures or skips
• clean Java 8 build, Javadocs and Eclipse generation
• reobfuscated production jar generated and reloaded the full surfaceprobe world under Forge 14.23.5.2859
• the same jar generated and reloaded successfully under official Cleanroom 0.6.10-alpha
• 13 structured resources parsed and all 16 locales retained 357-key parity
• artifact audit found the correct version and FMLAT metadata with no fixture or test leakage

A final quick CurseForge player launch, configure and explore as the manual acceptance gate.

Fixes #241