feat: Implement pagination and filtering for linked offers by integration

- Refactored `listLinkedOffersByIntegration` to `paginateLinkedOffersByIntegration` in `MarketplaceRepository`.
- Added pagination support with `page` and `per_page` filters.
- Introduced sorting options for offers.
- Created `listOfferChannelsByIntegration` method to retrieve distinct sales channels.
- Enhanced SQL queries to support dynamic filtering based on provided parameters.

feat: Add new fields for products and SKU generation

- Introduced new fields: `new_to_date`, `additional_message`, `additional_message_required`, and `additional_message_text` in the `products` table.
- Added `findAllSkus` method in `ProductRepository` to retrieve all SKUs.
- Created `ProductSkuGenerator` class to handle SKU generation based on a configurable format.
- Implemented `nextSku` method to generate the next available SKU.

feat: Enhance product settings management in the UI

- Added new settings page for product SKU format in `SettingsController`.
- Implemented form handling for saving SKU format settings.
- Updated the view to include SKU format configuration options.

feat: Implement cron job for refreshing ShopPro offer titles

- Created `ShopProOfferTitlesRefreshHandler` to handle the cron job for refreshing offer titles.
- Integrated with the `OfferImportService` to import offers from ShopPro.

docs: Update database schema documentation

- Added documentation for new fields in the `products` table and new cron job for offer title refresh.
- Documented the purpose and structure of the `app_settings` table.

migrations: Add necessary migrations for new features

- Created migration to add `products_sku_format` setting in `app_settings`.
- Added migration to introduce new fields in the `products` table.
- Created migration for the new cron job schedule for refreshing ShopPro offer titles.

DOCS/DB_SCHEMA.md

@@ -0,0 +1,119 @@
+# Struktura bazy danych (orderPRO)
+
+## Cel pliku
+- Ten dokument opisuje aktualny schemat bazy danych na podstawie migracji w `database/migrations`.
+- Aktualizuj ten plik przy każdej zmianie schematu (nowa tabela, kolumna, indeks, klucz obcy).
+
+## Tabele i przeznaczenie
+
+### `users`
+- Uzytkownicy panelu.
+- Klucz unikalny: `email`.
+
+### `products`
+- Glowna tabela produktow lokalnych.
+- Najwazniejsze pola: `type`, `sku`, `ean`, `status`, `promoted`, `vat`, `weight`, `price_*`, `quantity`.
+- Pola shopPRO: `new_to_date`, `additional_message`, `additional_message_required`, `additional_message_text`.
+- Dodatkowe: `producer_id`, `producer_name`, `product_unit_id`, `custom_fields_json`.
+- Soft delete: `deleted_at`.
+
+### `product_translations`
+- Globalne tresci produktu per jezyk (`lang`).
+- Najwazniejsze pola: `name`, `short_description`, `description`, SEO, `security_information`.
+- Unikalnosc: `(product_id, lang)`.
+
+### `product_integration_translations`
+- Nadpisania tresci produktu per integracja shopPRO.
+- Pola: `name`, `short_description`, `description` (NULL = fallback do `product_translations`).
+- Unikalnosc: `(product_id, integration_id)`.
+
+### `product_images`
+- Obrazy produktu (`storage_path`, `is_main`, `sort_order`).
+
+### `product_categories`
+- Relacja M:N produkt-kategoria (lokalna).
+
+### `attributes`
+- Definicje atrybutow wariantow.
+
+### `attribute_translations`
+- Tlumaczenia nazw atrybutow per jezyk.
+
+### `attribute_values`
+- Wartosci atrybutow (np. kolor, rozmiar), z opcjonalnym `impact_on_price`.
+
+### `attribute_value_translations`
+- Tlumaczenia wartosci atrybutow per jezyk.
+
+### `product_variants`
+- Warianty produktu.
+- Najwazniejsze pola: `permutation_hash`, `sku`, `ean`, `status`, `price_*`, `weight`, `stock_0_buy`.
+- Unikalnosc: `sku`, `(product_id, permutation_hash)`.
+
+### `product_variant_attributes`
+- Relacja wariant -> (atrybut, wartosc).
+- Klucz glowny: `(variant_id, attribute_id)`.
+
+### `product_change_log`
+- Log zmian produktow (audyt JSON: `before_json`, `after_json`).
+
+### `sales_channels`
+- Slownik kanalow sprzedazy (`shoppro`, `allegro`, `erli`, ...).
+
+### `product_channel_map`
+- Mapowanie lokalnego produktu do kanalu/integracji i ID zewnetrznych.
+- Najwazniejsze pola: `integration_id`, `external_product_id`, `external_variant_id`, `sync_state`, `link_type`, `link_status`, `confidence`.
+- Pola audytowe powiazania: `linked_at`, `linked_by_user_id`, `unlinked_at`, `unlinked_by_user_id`, `sync_meta_json`.
+
+### `channel_offers`
+- Cache ofert zewnetrznych dla integracji.
+- Najwazniejsze pola: `external_product_id`, `external_variant_id`, `external_offer_id`, `name` (tytul oferty), `sku`, `ean`, `offer_status`, `last_seen_at`, `payload_json`.
+- Unikalnosc: `(integration_id, external_product_id, external_variant_id)`.
+
+### `product_link_events`
+- Historia zdarzen na powiazaniach (`product_channel_map`).
+
+### `integrations`
+- Konfiguracja instancji integracji (obecnie shopPRO).
+- Najwazniejsze pola: `type`, `name`, `base_url`, `api_key_encrypted`, `timeout_seconds`, `is_active`.
+
+### `integration_test_logs`
+- Historia testow polaczen integracji.
+
+### `cron_jobs`
+- Kolejka jobow crona.
+
+### `cron_schedules`
+- Harmonogramy okresowych jobow.
+- Aktualnie zawiera m.in.:
+  - `product_links_health_check`
+  - `shoppro_offer_titles_refresh` (odswiezanie tytulow ofert; domyslnie co 30 dni)
+
+### `product_link_alerts`
+- Alerty zdrowia powiazan produktu.
+
+### `app_settings`
+- Ustawienia aplikacyjne key-value.
+- Przykładowe klucze: `cron_run_on_web`, `cron_web_limit`, `gs1_*`, `products_sku_format`.
+
+## Relacje (skrot)
+- `product_translations.product_id -> products.id`
+- `product_integration_translations.product_id -> products.id`
+- `product_integration_translations.integration_id -> integrations.id`
+- `product_images.product_id -> products.id`
+- `product_variants.product_id -> products.id`
+- `product_variant_attributes.variant_id -> product_variants.id`
+- `product_variant_attributes.attribute_id -> attributes.id`
+- `product_variant_attributes.value_id -> attribute_values.id`
+- `product_channel_map.product_id -> products.id`
+- `product_channel_map.channel_id -> sales_channels.id`
+- `product_channel_map.integration_id -> integrations.id`
+- `channel_offers.integration_id -> integrations.id`
+- `channel_offers.channel_id -> sales_channels.id`
+- `product_link_events.product_channel_map_id -> product_channel_map.id`
+- `product_link_alerts.product_channel_map_id -> product_channel_map.id`
+
+## Jak utrzymywac dokument
+1. Po dodaniu migracji zaktualizuj sekcje tabel/kolumn/relacji.
+2. Gdy dodajesz nowe klucze do `app_settings`, dopisz je tu.
+3. Przy zmianach harmonogramu crona zaktualizuj liste jobow w `cron_schedules`.