Show each entrypoint's last event and event count on the webhook page (closes #393)

Each entrypoint in the webhook page's entrypoint list shows when the last event arrived on its URL (relative, with the full UTC time on hover), or "never" if none ever has, and how many events arrived on it within the webhook's retention period. The last event is kept per entrypoint in a new EntrypointTotals row in the event database, written in the transaction that stores the event, so retention leaves it in place. The count is one query per page, grouped by entrypoint, over a new events index on entrypoint_id, deleted_at, resubmitted_from_id and created_at. Resubmitted copies did not arrive on the URL and count in neither. Pre-1.0: the table and index go into the schema in place.

Model: opus-5-5

internal/database/model_event.go

@@ -20,12 +20,15 @@ type Event struct {
 	// has no deleted_at condition and uses the index on created_at
 	// alone. The other tables keep the unindexed BaseModel created_at.
 	// DeletedAt is also the second column of the resubmitted_from_id
-	// index, for the reason DeliveryResult gives.
-	CreatedAt time.Time      `gorm:"index;index:idx_events_deleted_at_created_at,priority:2"                                           json:"createdAt"`
-	DeletedAt gorm.DeletedAt `gorm:"index:idx_events_deleted_at_created_at,priority:1;index:idx_events_resubmitted_from_id,priority:2" json:"deletedAt,omitzero"`
+	// index, for the reason DeliveryResult gives. The entrypoint_id
+	// index, for the webhook page's entrypoint list, has it second too,
+	// resubmitted_from_id third, and created_at last, which the list
+	// compares with a range.
+	CreatedAt time.Time      `gorm:"index;index:idx_events_deleted_at_created_at,priority:2;index:idx_events_entrypoint_id,priority:4"                                           json:"createdAt"`
+	DeletedAt gorm.DeletedAt `gorm:"index:idx_events_deleted_at_created_at,priority:1;index:idx_events_resubmitted_from_id,priority:2;index:idx_events_entrypoint_id,priority:2" json:"deletedAt,omitzero"`
 
-	WebhookID    string `gorm:"type:uuid;not null" json:"webhookId"`
-	EntrypointID string `gorm:"type:uuid;not null" json:"entrypointId"`
+	WebhookID    string `gorm:"type:uuid;not null"                                           json:"webhookId"`
+	EntrypointID string `gorm:"type:uuid;not null;index:idx_events_entrypoint_id,priority:1" json:"entrypointId"`
 
 	// Request data
 	Method      string `gorm:"not null"    json:"method"`
@@ -44,7 +47,7 @@ type Event struct {
 	// existed. It is not a foreign key: the source event can be
 	// reaped by retention while its copies remain, and the id is
 	// kept as the record of where the copy came from either way.
-	ResubmittedFromID *string `gorm:"type:uuid;index:idx_events_resubmitted_from_id,priority:1" json:"resubmittedFromId,omitempty"`
+	ResubmittedFromID *string `gorm:"type:uuid;index:idx_events_resubmitted_from_id,priority:1;index:idx_events_entrypoint_id,priority:3" json:"resubmittedFromId,omitempty"`
 
 	// Relations. No model marshals the record it belongs to, so
 	// Webhook and Entrypoint are left out of the JSON.