feat(23-shipment-presets-backend): tabela DB, repository CRUD i JSON API dla presetów przesyłek

Phase 23 complete:
- Migracja shipment_presets (16 kolumn: name, color, carrier, wymiary, waga, itp.)
- ShipmentPresetRepository z findAll/findById/create/update/delete
- ShipmentPresetController z 4 endpointami JSON API
- Routing w routes/web.php z auth middleware

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

database/migrations/20260322_000059_create_shipment_presets_table.sql

@@ -0,0 +1,20 @@
+CREATE TABLE IF NOT EXISTS shipment_presets (
+    id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+    name VARCHAR(100) NOT NULL,
+    color VARCHAR(7) NOT NULL DEFAULT '#3b82f6',
+    carrier VARCHAR(32) NOT NULL COMMENT 'allegro, inpost, apaczka',
+    provider_code VARCHAR(32) NOT NULL COMMENT 'allegro_wza, apaczka, inpost',
+    delivery_method_id VARCHAR(128) NOT NULL,
+    credentials_id VARCHAR(128) NOT NULL DEFAULT '',
+    carrier_id VARCHAR(64) NOT NULL DEFAULT '',
+    package_type VARCHAR(16) NOT NULL DEFAULT 'PACKAGE',
+    length_cm DECIMAL(8,1) NOT NULL DEFAULT 25.0,
+    width_cm DECIMAL(8,1) NOT NULL DEFAULT 20.0,
+    height_cm DECIMAL(8,1) NOT NULL DEFAULT 8.0,
+    weight_kg DECIMAL(8,3) NOT NULL DEFAULT 1.000,
+    sender_point_id VARCHAR(64) NOT NULL DEFAULT '',
+    label_format VARCHAR(8) NOT NULL DEFAULT 'PDF',
+    sort_order INT UNSIGNED NOT NULL DEFAULT 0,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;