feat: implement revision retention settings and pruning logic

Added functionality to handle revision retention minutes in global settings, including validation for input values. Introduced a new method to prune old revisions based on the specified retention period, ensuring that only the most recent revisions are kept. Updated the frontend to allow users to configure the revision retention setting, enhancing the management of revision lifecycles.

internal/repository/postgres.go

@@ -784,6 +784,32 @@ func (p *Postgres) RevisionDiff(tenantID, aID, bID string) (map[string]any, erro
 	}, nil
 }
 
+func (p *Postgres) PruneRevisionsBefore(tenantID string, cutoff time.Time) (int, error) {
+	ctx := context.Background()
+	cmd, err := p.pool.Exec(ctx, `
+		DELETE FROM config_revision AS cr
+		WHERE cr.tenant_id = $1
+		  AND cr.created_at < $2
+		  AND cr.id <> (
+			SELECT id
+			FROM config_revision
+			WHERE tenant_id = $1
+			ORDER BY created_at DESC
+			LIMIT 1
+		  )
+		  AND NOT EXISTS (
+			SELECT 1
+			FROM bgp_speaker AS sp
+			WHERE sp.tenant_id = $1
+			  AND (sp.last_applied_revision_id = cr.id OR sp.published_revision_id = cr.id)
+		  )`,
+		tenantID, cutoff.UTC())
+	if err != nil {
+		return 0, err
+	}
+	return int(cmd.RowsAffected()), nil
+}
+
 func (p *Postgres) SetLastAppliedRevision(tenantID, speakerID, revisionID string) error {
 	ctx := context.Background()
 	tag, err := p.pool.Exec(ctx, `