Add GitHub Pages deployment workflow for both apps

- Deploy marketing-site to root (/)
- Deploy main-app to /app/ subdirectory
- Build both apps and combine into single GitHub Pages deployment
- Add comprehensive deployment documentation
- Workflow runs on push to main branch or manually via workflow_dispatch

Author: martinmeerAT

.github/workflows/deploy-github-pages.yml

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+name: Deploy to GitHub Pages
+
+on:
+  push:
+    branches: ["main"]
+  workflow_dispatch:
+
+# Sets permissions for GitHub Pages deployment
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# Allow only one concurrent deployment
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  build-and-deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # Build Marketing Site
+      - name: Setup Node.js for Marketing Site
+        uses: actions/setup-node@v4
+        with:
+          node-version: '18'
+          cache: 'npm'
+          cache-dependency-path: apps/marketing-site/package-lock.json
+
+      - name: Install Marketing Site dependencies
+        working-directory: apps/marketing-site
+        run: npm ci
+
+      - name: Build Marketing Site
+        working-directory: apps/marketing-site
+        run: npm run build
+
+      # Build Main App
+      - name: Install Main App dependencies
+        working-directory: apps/main-app
+        run: npm ci
+
+      - name: Build Main App
+        working-directory: apps/main-app
+        run: npm run build
+
+      # Prepare deployment directory
+      - name: Prepare GitHub Pages content
+        run: |
+          mkdir -p _site
+          # Copy marketing site to root
+          cp -r apps/marketing-site/dist/* _site/
+          # Copy main app to /app subdirectory
+          mkdir -p _site/app
+          cp -r apps/main-app/dist/* _site/app/
+          # Copy shared assets if needed
+          if [ -d "packages/shared/img" ]; then
+            mkdir -p _site/shared/img
+            cp -r packages/shared/img/* _site/shared/img/
+          fi
+          # Ensure .nojekyll exists
+          touch _site/.nojekyll
+          echo "Deployment structure:"
+          ls -la _site/
+          echo "Main app content:"
+          ls -la _site/app/ || echo "No app directory"
+
+      - name: Setup Pages
+        uses: actions/configure-pages@v5
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: './_site'
+
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4
+

GITHUB_PAGES_DEPLOYMENT.md

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+# GitHub Pages Deployment Guide
+
+## Deployment Structure
+
+This monorepo deploys both applications to GitHub Pages:
+
+```
+https://your-username.github.io/your-repo/
+├── /                    → Marketing Site (apps/marketing-site)
+└── /app/                → Main Application (apps/main-app)
+```
+
+## URLs
+
+- **Marketing Site**: `https://your-username.github.io/your-repo/`
+- **Main Application**: `https://your-username.github.io/your-repo/app/`
+
+## Setup Instructions
+
+### 1. Enable GitHub Pages
+
+1. Go to your repository on GitHub
+2. Navigate to **Settings** → **Pages**
+3. Under "Build and deployment":
+   - **Source**: Select **"GitHub Actions"** (not "Deploy from a branch")
+   - This is crucial - it prevents automatic Jekyll builds
+
+### 2. Deploy
+
+The deployment happens automatically when you push to the `main` branch:
+
+```bash
+git push origin main
+```
+
+### 3. Manual Deployment
+
+You can also trigger a deployment manually:
+1. Go to **Actions** tab on GitHub
+2. Select **"Deploy to GitHub Pages"** workflow
+3. Click **"Run workflow"**
+
+## How It Works
+
+1. **Build Phase**:
+   - Marketing site is built (`apps/marketing-site → dist/`)
+   - Main app is built (`apps/main-app → dist/`)
+
+2. **Deployment Phase**:
+   - Marketing site deployed to root (`/`)
+   - Main app deployed to `/app/` subdirectory
+   - Shared assets copied to `/shared/`
+   - `.nojekyll` file added to skip Jekyll processing
+
+## Local Testing
+
+### Marketing Site
+```bash
+cd apps/marketing-site
+npm run dev
+```
+
+### Main App
+```bash
+cd apps/main-app
+npm run dev
+```
+
+## Troubleshooting
+
+### Jekyll Errors
+
+If you see Jekyll-related errors like:
+```
+Error: No such file or directory @ rb_check_realpath_internal
+```
+
+**Solution**: Ensure GitHub Pages is set to **"GitHub Actions"** mode (not "Deploy from a branch").
+
+### 404 Errors
+
+If pages show 404:
+1. Check that the workflow completed successfully in the **Actions** tab
+2. Verify the build outputs exist in the workflow logs
+3. Ensure paths in your HTML/JS match the deployment structure
+
+### Asset Loading Issues
+
+If assets don't load in the deployed app:
+- Marketing site assets should use root-relative paths: `/assets/...`
+- Main app assets should use: `/app/assets/...`
+
+## CI/CD Workflows
+
+- **`deploy-github-pages.yml`**: Deploys to GitHub Pages (runs on `main` branch)
+- **`main-app-ci.yml`**: CI for main app (build, test, Docker)
+- **`marketing-site-ci.yml`**: CI for marketing site (build, test, Docker)
+
+## Notes
+
+- The `.nojekyll` file disables Jekyll processing
+- `_config.yml` and `.jekyllignore` are kept as fallbacks
+- Both apps maintain independent build processes
+- Docker deployments remain separate from GitHub Pages
+