Introduce selectable webhook payload formats and Google Chat rich-card support. NotificationGroupController now reads and validates a webhook_format option (generic, google_chat, simple_text) and logs a warning if Google Chat format is chosen but the URL does not look like chat.googleapis.com. WebhookChannel gains format constants, a payload builder (generic/simple text/Google Chat card), improved Content-Type header, enhanced logging with masked URLs, response truncation, payload previews, and better RequestException handling. Views updated to expose a Webhook Format dropdown, contextual help (including Google Chat setup instructions), dynamic placeholders/help text, and include the selected format when testing/saving webhooks. These changes add format flexibility and improve observability and safety when sending webhook notifications.
Replaced error_log calls with structured logging using the Logger class in DiscordChannel, SlackChannel, TelegramChannel, and WebhookChannel. Log success and error cases with relevant context for improved observability and debugging.
Introduces a new 'Webhook (Custom)' notification channel allowing users to send JSON payloads to any HTTP endpoint (e.g., n8n, Zapier, custom APIs). Updates the UI to support webhook configuration, adds backend validation, and implements the WebhookChannel for sending notifications. Documentation is updated with usage instructions and payload examples.
