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/SERVER_SETUP.md

@@ -0,0 +1,118 @@
+# Server Setup (Manual)
+
+Since sudo prompts don't work over SSH in justfile, do the initial setup manually.
+
+## One-Time Setup on Server
+
+```bash
+# 1. SSH to server
+ssh posterg
+
+# 2. Backup current site (recommended)
+sudo cp -r /var/www/html /var/www/html.backup
+
+# 3. Create new directory structure
+sudo mkdir -p /var/www/posterg
+
+# 4. Set ownership (www-data is the web server user)
+sudo chown www-data:posterg /var/www/posterg
+
+# 5. Set permissions (775 = rwxrwxr-x)
+sudo chmod 775 /var/www/posterg
+
+# 6. Verify
+ls -ld /var/www/posterg
+# Should show: drwxrwxr-x 2 www-data posterg 4096 ... /var/www/posterg
+
+# 7. Exit server
+exit
+```
+
+## Deploy from Local Machine
+
+```bash
+just deploy
+```
+
+## Complete Deployment Process
+
+```bash
+# On server (one time)
+ssh posterg
+sudo mkdir -p /var/www/posterg
+sudo chown www-data:posterg /var/www/posterg
+sudo chmod 775 /var/www/posterg
+exit
+
+# From local machine
+just deploy           # Deploy files
+just deploy-nginx     # Update nginx config
+
+# On server - apply nginx config
+ssh posterg
+sudo bash /tmp/deploy-production.sh
+sudo systemctl reload nginx
+exit
+
+# Verify from local
+just server-status
+```
+
+## Important Notes
+
+- **Don't delete `/var/www/html/` yet!** Keep it as backup until you confirm the new structure works
+- The new structure uses `/var/www/posterg/public/` as DocumentRoot
+- Nginx must be updated to point to the new location
+
+## After Confirming Everything Works
+
+Once you've verified the new deployment works:
+
+```bash
+ssh posterg
+sudo rm -rf /var/www/html.backup  # Remove backup if no longer needed
+sudo rm -rf /var/www/html          # Remove old directory
+```
+
+## Directory Structure on Server
+
+```
+/var/www/
+├── html/              ← OLD (keep as backup for now)
+├── html.backup/       ← BACKUP (can delete later)
+└── posterg/           ← NEW
+    ├── public/        ← DocumentRoot (nginx serves from here)
+    ├── includes/
+    ├── config/
+    ├── database/
+    ├── lib/
+    └── vendor/
+```
+
+## Troubleshooting
+
+### Permission denied during deploy
+**Cause:** Directory doesn't exist or has wrong ownership  
+**Fix:** Run the setup commands above
+
+### Nginx 403 Forbidden
+**Cause:** Wrong permissions on files  
+**Fix:**
+```bash
+ssh posterg
+cd /var/www/posterg
+sudo chown -R www-data:posterg .
+sudo find . -type d -exec chmod 755 {} \;
+sudo find . -type f -exec chmod 644 {} \;
+sudo chmod 775 database/
+sudo chmod 660 database/*.db
+```
+
+### Database connection errors
+**Cause:** Database file permissions  
+**Fix:**
+```bash
+ssh posterg
+sudo chown www-data:posterg /var/www/posterg/database/test.db
+sudo chmod 660 /var/www/posterg/database/test.db
+```