feat: webhook stats

[danielhe4rt]

Currently, there is no visibility into the volume and distribution of inbound webhooks received per provider. This makes it difficult for admins to understand which integrations are actively sending data and at what rate. Adding a stats widget will provide quick insight into webhook activity, allowing for faster troubleshooting and monitoring.

Proposed Idea

Implement a new Filament widget at Filament/Admin/Widgets/InboundWebhookStatsBySource.

This widget will:

• Track inbound webhooks grouped by source.
• Display the percentage of received webhooks for each provider.
• Show a fractional description (e.g., “1 of 10 webhooks in this provider”) to make the data more understandable.
• Be part of the ListInboundWebhooks.

Acceptance Criteria

• A Filament widget exists at Filament/Admin/Widgets/InboundWebhookStatsBySource.
• The widget retrieves inbound webhook data from the ListInboundWebhooks resource.
• The widget groups webhooks by provider/source.
• For each provider, the widget shows:
  • Total number of webhooks received.
  • Percentage of the total webhooks this represents.
  • A description string in the format “X of Y webhooks”.