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/obsidian-tasks-plugin/manifest.json

@@ -0,0 +1,12 @@
+{
+  "id": "obsidian-tasks-plugin",
+  "name": "Tasks",
+  "version": "7.23.1",
+  "minAppVersion": "1.4.0",
+  "description": "Track tasks across your vault. Supports due dates, recurring tasks, done dates, sub-set of checklist items, and filtering.",
+  "helpUrl": "https://publish.obsidian.md/tasks/",
+  "author": "Clare Macrae and Ilyas Landikov (created by Martin Schenck)",
+  "authorUrl": "https://github.com/obsidian-tasks-group",
+  "fundingUrl": "https://github.com/sponsors/claremacrae",
+  "isDesktopOnly": false
+}