Rebrand application from Obsidian to Warehouse13

- Update main app title in Angular frontend
- Update FastAPI application title and API endpoints
- Update static HTML index page
- Update all quickstart scripts (bash, PowerShell, batch)
- Update README files (main and frontend)
- Maintain ◆ symbol in headers

All references to "Obsidian" have been replaced with "Warehouse13" throughout the application.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

quickstart.sh

@@ -3,7 +3,7 @@
 set -e
 
 echo "========================================="
-echo "Obsidian - Quick Start"
+echo "Warehouse13 - Quick Start"
 echo "========================================="
 echo ""