chore: initialize homebrew-magic-rpg monorepo

Consolidates the HbM: RPG project (formerly the loose hbm-books
working folder) into a single repo. ObsidianNotes, foundry-lore, and
foundry-system are wired in as submodules pointing at their existing
Gitea repos. Loose tooling scripts are organized under tools/,
obsolete/one-off scripts (fix_vault.py, generate_mocs.py, debug-*.ts,
write_file_helper.py) and _books/ (superseded by ObsidianNotes) are
excluded via .gitignore rather than deleted. foundryvtt-admin is
excluded pending its own separate repo.

.gitmodules

@@ -0,0 +1,9 @@
+[submodule "Foundry-Data/foundry-lore"]
+	path = Foundry-Data/foundry-lore
+	url = https://git.octoturge.com/octoturge/hbm-foundry-lore.git
+[submodule "Foundry-Data/foundry-system"]
+	path = Foundry-Data/foundry-system
+	url = https://git.octoturge.com/octoturge/hbm-foundry-system.git
+[submodule "ObsidianNotes"]
+	path = ObsidianNotes
+	url = https://git.octoturge.com/octoturge/hbm-obsidian.git