refactor: restructure project into muxplex/ subdir with brand integration

- Move coordinator/, frontend/, Caddyfile, pyproject.toml, requirements.txt,
  docs/ into muxplex/ subdir in prep for packaging/sharing
- Add brand assets to frontend/: favicon.ico, pwa-192/512.png,
  apple-touch-icon.png, wordmark-on-dark.svg
- Update app: title → muxplex, header → wordmark SVG, brand color tokens
  in style.css, manifest.json updated with muxplex name and brand icons
- Add design system: assets/branding/tokens.css (101 CSS custom properties),
  tokens.json (127 tokens), DESIGN-SYSTEM.md (856-line spec)
- Add assets/branding/: SVG sources, rendered PNGs (icons, favicons, PWA, OG)
- Add scripts/render-brand-assets.py for reproducible PNG generation
- Add muxplex/README.md

README.md

@@ -0,0 +1,45 @@
+# muxplex
+
+A web-based dashboard for tmux sessions. Access and manage all your tmux sessions from any device — browser, phone, tablet.
+
+## Features
+- Live tile grid showing all running tmux sessions  
+- Click any session to open a full interactive terminal
+- Bell/activity notifications across sessions
+- Multi-device support with state sync
+- Mobile-friendly, responsive, PWA-capable
+- Works over Tailscale private network
+
+## Stack
+- **Backend:** Python FastAPI coordinator (`coordinator/`)
+- **Frontend:** Vanilla JS + xterm.js (`frontend/`)
+- **Terminal:** ttyd (WebSocket bridge to tmux)
+- **Proxy:** Caddy
+
+## Running
+
+```bash
+# Install dependencies
+pip install -r requirements.txt
+
+# Start coordinator (from this directory)
+python -m uvicorn coordinator.main:app --host 0.0.0.0 --port 8099
+
+# Start Caddy proxy
+caddy run --config Caddyfile
+```
+
+## Development
+
+```bash
+# Run tests
+python -m pytest
+```
+
+## Brand assets
+
+Design language, tokens, and brand assets in `assets/branding/`.
+To regenerate PNG/favicon assets from SVG sources:
+```bash
+python3 scripts/render-brand-assets.py
+```