chore: remove vibe-coding artifacts from tracking, sync notes and obsidian config

- Untrack .claude/launch.json (Claude Code config)
- Add .claude/, .mcp.json, CLAUDE.md, and AI-generated CSVs to .gitignore
- Add _notes/ vault (architecture, API, tasks, bugs, infra docs)
- Add .obsidian/ plugin/vault config (workspace state excluded)
- Sync CHANGELOG.md

.obsidian/community-plugins.json

@@ -0,0 +1,7 @@
+[
+  "dataview",
+  "obsidian-kanban",
+  "templater-obsidian",
+  "calendar",
+  "obsidian-tasks-plugin"
+]