Backport Phase 3 release to Forge 1.15.2

[SkyBlade1978]

Summary

• bring the Forge 1.15.2 branch up to the IronAgeFurniture Phase 3 lighting release at version 0.3.0.115021
• preserve the existing furniture and optional Biomes O' Plenty, Oh The Biomes You'll Go, and Immersive Engineering integrations
• correct recipe unlocking and recipe-book grouping, thrown lava-lamp rendering, sconce support, obsidian inventory rendering, waterlogged lava sconces, and optional ObjectHolder startup noise
• add the documented migration bridge for supported Forge 1.10.2 and 1.12.2 worlds, including multicolour padded benches and the 1.12 Oh The Biomes add-on
• modernize the reproducible build, Eclipse setup, release artifacts, checksums, and hosted validation for this branch

Verification

• clean check build javadoc verifyReleaseArtifacts verifyReleaseChecksums
• generated and audited all Eclipse client, server, data, and test launches
• validated 12,058 resource JSON documents and 6,342 locale keys
• packaged optional-integration server probe passed with BOP, BYG, and IE: 1,286 recipes and 1,286 advancements
• repository-hygiene and workflow-pin checks passed; no agent notes, local worlds, caches, or machine-specific paths are included
• manual Eclipse testing confirmed the latest recipe-unlock and optional ObjectHolder fixes

This PR only integrates the tested branch. It does not tag or publish a release.