Update README.md

Document requirement for Obsidian to be running

Fix configuration architecture for Obsidian folder structure

Fix MCP setup: settings.local.json must be in .claude/ directory

Fix Mermaid diagrams for GitHub compatibility

Enhance README with comprehensive architecture visualizations

Simplify setup to clone-and-configure workflow

Add /switch-brain command for vault switching

Update Quick Start to use settings.md.template

Add settings.md.template and ignore local config files

Clarify MCP configuration requirement in Quick Start

Update docs to use settings.md configuration

Simplify to single vault path configuration

Simplify settings.md to clean key-value configuration

Add centralized vault path configuration system