Substantial bible expansion (frontmatter, Obsidian list/heading formatting,
expanded core themes section, target length 25–28 rooms).
Adds .obsidian/ vault config (app/appearance/core-plugins) and gitignore
rules for the per-machine workspace cache, mirroring the world vault setup.
Done before extracting Halfstreet to its own repo so this work travels with
the filter-repo extraction.
