Initial commit: Dispensa - home pantry management app

Features:
- Barcode scanning (QuaggaJS) + Open Food Facts API lookup
- Inventory management with locations (Frigo, Freezer, Dispensa)
- Product database with Italian product suggestions
- Expiry date estimation by category
- AI expiry date reading via Gemini Vision API
- Flexible unit of measure (pz, conf, g, kg, ml, L)
- Nutriscore/NOVA/Ecoscore/allergens display
- Mobile-first PWA with offline support
- SQLite backend with PHP REST API

api/database.php

@@ -0,0 +1,66 @@
+<?php
+/**
+ * Database initialization and connection for Dispensa Manager
+ */
+
+define('DB_PATH', __DIR__ . '/../data/dispensa.db');
+
+function getDB(): PDO {
+    $isNew = !file_exists(DB_PATH);
+    $db = new PDO('sqlite:' . DB_PATH);
+    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+    $db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
+    $db->exec("PRAGMA journal_mode=WAL");
+    $db->exec("PRAGMA foreign_keys=ON");
+    
+    if ($isNew) {
+        initializeDB($db);
+    }
+    return $db;
+}
+
+function initializeDB(PDO $db): void {
+    $db->exec("
+        CREATE TABLE IF NOT EXISTS products (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            barcode TEXT UNIQUE,
+            name TEXT NOT NULL,
+            brand TEXT DEFAULT '',
+            category TEXT DEFAULT '',
+            image_url TEXT DEFAULT '',
+            unit TEXT DEFAULT 'pz',
+            default_quantity REAL DEFAULT 1,
+            notes TEXT DEFAULT '',
+            created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+            updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+        );
+
+        CREATE TABLE IF NOT EXISTS inventory (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            product_id INTEGER NOT NULL,
+            location TEXT NOT NULL DEFAULT 'dispensa',
+            quantity REAL NOT NULL DEFAULT 1,
+            expiry_date DATE,
+            added_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+            updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+            FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE
+        );
+
+        CREATE TABLE IF NOT EXISTS transactions (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            product_id INTEGER NOT NULL,
+            type TEXT NOT NULL CHECK(type IN ('in', 'out')),
+            quantity REAL NOT NULL,
+            location TEXT NOT NULL DEFAULT 'dispensa',
+            notes TEXT DEFAULT '',
+            created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+            FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE
+        );
+
+        CREATE INDEX IF NOT EXISTS idx_products_barcode ON products(barcode);
+        CREATE INDEX IF NOT EXISTS idx_inventory_product ON inventory(product_id);
+        CREATE INDEX IF NOT EXISTS idx_inventory_location ON inventory(location);
+        CREATE INDEX IF NOT EXISTS idx_transactions_product ON transactions(product_id);
+        CREATE INDEX IF NOT EXISTS idx_transactions_date ON transactions(created_at);
+    ");
+}