Port IronAgeFurniture to Forge 1.21.1

[SkyBlade1978]

Summary

• port Iron Age Furniture from Forge 1.20.6 to Minecraft 1.21.1 / Forge 52.1.0 on Java 21
• retain the ironagefurniture runtime identity, zone.moddev.mc Maven coordinates, four-part 0.3.0.121011 version, deterministic release artifacts, Eclipse setup, and guarded CI/release flow
• retain optional Biomes O' Plenty and Oh The Biomes We've Gone furniture (including Spirit wood) while intentionally omitting unsupported Immersive Engineering integration on this target
• carry forward ingredient-specific recipe advancements, correct furniture flammability with fireproof Nether woods, and throwable/shattering lava lamps
• correct BOP/BWG/vanilla texture mappings and validate optional integration models directly against pinned compatible mod jars

Verification

• full isolated local Gradle release gate: clean, checks, build, Javadoc, artifact/checksum/prepared-bundle, Maven coordinate, repository hygiene, namespace, metadata, resource, workflow, and Eclipse verification
• 15,032 runtime JSON files parsed; 7,062 locale keys checked; 1,482 conditional recipes and matching advancements checked
• 7,187 BOP/BWG-backed block models resolved against pinned compatible integration jars
• exact main, sources, and Javadoc release bundle prepared and audited
• Eclipse/Buildship metadata generated and production classpath verified against Temurin 21.0.7+6
• manual Minecraft 1.21.1 gameplay testing completed by the maintainer

Publication is not performed by this PR; the protected default-branch release dispatcher will be started only after merge and green checks.