chore(halfstreet): bible Obsidian-formatted edits + vault config

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.

docs/superpowers/specs/.obsidian/app.json

@@ -0,0 +1 @@
+{}