Add commit URL to Slack notifications with link and backtick formatting

- Add commit_url column to webhook_events and deployments tables
- Extract commit URL from webhook payload (from commit object or repo URL)
- Format Slack messages with backticks for branch and commit SHA
- Link commit SHA to the actual commit URL on the git server
- Keep plain text format for ntfy notifications

internal/service/deploy/deploy.go

@@ -439,9 +439,15 @@ func (svc *Service) createDeploymentRecord(
 		}
 	}
 
-	// Set commit SHA from webhook event
-	if webhookEvent != nil && webhookEvent.CommitSHA.Valid {
-		deployment.CommitSHA = webhookEvent.CommitSHA
+	// Set commit SHA and URL from webhook event
+	if webhookEvent != nil {
+		if webhookEvent.CommitSHA.Valid {
+			deployment.CommitSHA = webhookEvent.CommitSHA
+		}
+
+		if webhookEvent.CommitURL.Valid {
+			deployment.CommitURL = webhookEvent.CommitURL
+		}
 	}
 
 	deployment.Status = models.DeploymentStatusBuilding