add gitignore and commit Obsidian vault config

Exclude .env (a GOOGLE_CLOUD_PROJECT value was present at the repo root),
.claude/settings.local.json, OS cruft, and personal Obsidian workspace
state (workspace.json, workspace-mobile.json, cache). Commit the rest of
.obsidian/ so the vault reopens with the same plugins, graph settings,
and daily-notes config on any machine.

Also expand Obsidian's userIgnoreFilters so .claude, .env, and .gitignore
don't pollute the file explorer, search, or graph view.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.obsidian/plugins/show-diff/manifest.json

@@ -0,0 +1,11 @@
+{
+	"id": "show-diff",
+	"name": "Show Diff",
+	"version": "0.1.0",
+	"minAppVersion": "0.15.0",
+	"description": "Render Git diffs in Obsidian files",
+	"author": "Ivan Lednev",
+	"authorUrl": "https://github.com/ivan-lednev",
+	"fundingUrl": "https://www.buymeacoffee.com/machineelf",
+	"isDesktopOnly": true
+}