Fix admin CSS not loading and quirks mode issues

Fixed multiple issues in admin panel:

1. CSS path: modern-normalize.css → modern-normalize.min.css
   (File is actually named .min.css)

2. Icon path: assets/icon.svg → /assets/admin_favicon.svg
   (Was relative, now absolute; correct filename)

3. Navigation: /admin/list.php → /admin/
   (list.php was renamed to index.php)

4. Short PHP tags: <? → <?php
   (Better compatibility, some servers don't enable short_open_tag)

5. Quirks mode warning was due to CSS not loading, not DOCTYPE
   (DOCTYPE was already present)

Files modified:
- public/admin/inc/head.php (main fixes)
- public/admin/index.php (short tags)
- public/admin/add.php (short tags)
- public/admin/import.php (short tags)

Need to redeploy for production: just deploy

docs/DEPLOYMENT_STEPS.md

@@ -0,0 +1,215 @@
+# Deployment Steps
+
+## First-Time Deployment (New Structure)
+
+Since we're moving from `/var/www/html/` to `/var/www/posterg/`, follow these steps:
+
+### 1. Setup Server Directory (ONE TIME)
+
+```bash
+just setup-server
+```
+
+This creates `/var/www/posterg/` with correct permissions:
+- Owner: `www-data:posterg`
+- Permissions: `775`
+
+### 2. Deploy Application
+
+```bash
+just deploy
+```
+
+This deploys all files to `/var/www/posterg/`:
+- `public/` → `/var/www/posterg/public/`
+- `includes/` → `/var/www/posterg/includes/`
+- `config/` → `/var/www/posterg/config/`
+- `database/` → `/var/www/posterg/database/`
+- `lib/` → `/var/www/posterg/lib/`
+
+### 3. Update Nginx Configuration
+
+```bash
+just deploy-nginx
+```
+
+This checks that nginx config has correct DocumentRoot and uploads it to server.
+
+**IMPORTANT:** The nginx config must have:
+```nginx
+root /var/www/posterg/public;
+```
+
+If the check fails, edit `nginx/posterg.conf` first.
+
+### 4. Apply Nginx Configuration on Server
+
+```bash
+ssh posterg
+sudo bash /tmp/deploy-production.sh
+sudo systemctl reload nginx
+```
+
+### 5. Verify Deployment
+
+```bash
+just server-status
+```
+
+Check:
+- https://posterg.erg.be/ (should work)
+- https://posterg.erg.be/admin/ (should work)
+- https://posterg.erg.be/database/test.db (should 404 ✅)
+
+---
+
+## Subsequent Deployments
+
+After the first deployment, you only need:
+
+```bash
+just deploy
+```
+
+That's it! The directory structure is already in place.
+
+---
+
+## Deploy Database
+
+If you need to deploy the database:
+
+```bash
+just deploy-database
+```
+
+This will:
+1. Upload `database/test.db` to server
+2. Set correct permissions
+3. Warn before overwriting
+
+---
+
+## Troubleshooting
+
+### Permission Denied on Deploy
+
+**Error:**
+```
+mkdir "/var/www/posterg" failed: Permission denied (13)
+```
+
+**Solution:**
+```bash
+just setup-server
+```
+
+### Nginx 500 Error
+
+**Cause:** Nginx DocumentRoot still pointing to old location
+
+**Solution:**
+1. Check nginx config has: `root /var/www/posterg/public;`
+2. Redeploy nginx config:
+   ```bash
+   just deploy-nginx
+   ssh posterg
+   sudo bash /tmp/deploy-production.sh
+   sudo systemctl reload nginx
+   ```
+
+### Database Connection Errors
+
+**Cause:** Database file permissions incorrect
+
+**Solution:**
+```bash
+ssh posterg
+cd /var/www/posterg
+sudo chown www-data:posterg database/test.db
+sudo chmod 660 database/test.db
+```
+
+### Admin 404
+
+**Cause:** Nginx still using old `/formulaire/` location
+
+**Solution:** Update `nginx/posterg.conf` to use `/admin/` location
+
+---
+
+## Rollback
+
+If something goes wrong, rollback is easy:
+
+### 1. Restore Old Directory
+
+```bash
+ssh posterg
+sudo cp -r /var/www/html.backup /var/www/html  # If you backed up
+```
+
+### 2. Restore Old Nginx Config
+
+```bash
+ssh posterg
+sudo cp /etc/nginx/sites-available/posterg.backup /etc/nginx/sites-available/posterg
+sudo systemctl reload nginx
+```
+
+### 3. Rollback Code with jj
+
+```bash
+jj log
+jj edit <previous-change-id>
+```
+
+---
+
+## Migration Checklist
+
+- [ ] `just setup-server` - Create server directory
+- [ ] `just deploy` - Deploy application
+- [ ] `just deploy-nginx` - Update nginx config
+- [ ] SSH to server and apply nginx config
+- [ ] `sudo systemctl reload nginx`
+- [ ] Verify site works: https://posterg.erg.be/
+- [ ] Verify security: https://posterg.erg.be/database/test.db → 404
+- [ ] Test admin: https://posterg.erg.be/admin/
+- [ ] Deploy database (if needed): `just deploy-database`
+
+---
+
+## Commands Reference
+
+| Command | Purpose |
+|---------|---------|
+| `just setup-server` | Create `/var/www/posterg/` (first time only) |
+| `just deploy` | Deploy application files |
+| `just deploy-nginx` | Update nginx configuration |
+| `just deploy-database` | Deploy database file |
+| `just server-status` | Check server health |
+| `just server-logs` | View server logs |
+
+---
+
+## Directory Structure on Server
+
+```
+/var/www/posterg/               # Application root (private)
+├── public/                     # DocumentRoot (nginx points here)
+│   ├── index.php
+│   ├── search.php
+│   ├── memoire.php
+│   ├── admin/
+│   └── assets/
+├── includes/                   # Templates (private)
+├── config/                     # Configuration (private)
+├── database/                   # Database (private)
+├── lib/                        # PHP classes (private)
+└── vendor/                     # Dependencies (private)
+```
+
+**Nginx DocumentRoot:** `/var/www/posterg/public/`
+
+Only the `public/` directory is accessible via web browser. Everything else is private.