Setup PatternFly React project infrastructure

[itdove]

Description

Set up the foundational infrastructure for the PatternFly React web UI.

Tasks

• Create devflow/web/ directory structure
• Initialize React + Vite project in devflow/web/frontend/
• Install PatternFly dependencies
• Configure TypeScript
• Set up build pipeline (Vite config)
• Create Flask backend scaffold
• Add daf config web command to CLI
• Configure static file serving

Acceptance Criteria

• Running npm run dev starts dev server
• Running npm run build creates production build
• Running daf config web starts Flask server and opens browser
• PatternFly CSS loads correctly
• TypeScript compilation works without errors

Estimated Effort: 3-5 days

[itdove]

Child of #305