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/app.json

@@ -0,0 +1,12 @@
+{
+  "useMarkdownLinks": true,
+  "newFileLocation": "folder",
+  "newFileFolderPath": "_notes/08 - Meetings & Notes",
+  "attachmentFolderPath": "_notes/assets",
+  "defaultViewMode": "source",
+  "foldHeading": false,
+  "showLineNumber": true,
+  "readableLineLength": true,
+  "strictLineBreaks": false,
+  "showFrontmatter": false
+}