fusion/.changeset/update-documentation-references.md

@gsxdsm/fusion, @fusion/core, @fusion/dashboard, @fusion/engine

@gsxdsm/fusion	@fusion/core	@fusion/dashboard	@fusion/engine
patch	patch	patch	patch

Update documentation and remaining references for Fusion rebrand

• Updated AGENTS.md with new package names and commit conventions
• Updated README.md with FN-XXX task ID format and fusion/ branch naming
• Updated RELEASING.md with new package filters
• Updated package README files with consistent branding
• Completed KB-335 environment variable rename (KB_* → FUSION_*)