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

scripts/install-php-sqlite.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+# Install PHP SQLite extension
+
+echo "🔧 Installing PHP SQLite extension..."
+
+# Check if running as root
+if [ "$EUID" -ne 0 ]; then
+    echo "Error: This script must be run as root (use sudo)"
+    exit 1
+fi
+
+# Detect PHP version
+PHP_VERSION=$(php -r "echo PHP_MAJOR_VERSION.'.'.PHP_MINOR_VERSION;")
+echo "Detected PHP version: $PHP_VERSION"
+
+# Install SQLite extension
+echo "Installing php${PHP_VERSION}-sqlite3..."
+apt-get update -qq
+apt-get install -y php${PHP_VERSION}-sqlite3
+
+# Restart PHP-FPM
+echo "Restarting PHP-FPM..."
+systemctl restart php${PHP_VERSION}-fpm
+
+# Verify installation
+if php -m | grep -q sqlite3; then
+    echo "✅ SQLite extension installed successfully"
+    echo ""
+    echo "Installed extensions:"
+    php -m | grep -i sqlite
+else
+    echo "❌ Failed to install SQLite extension"
+    exit 1
+fi