allow handles to start with a number (#1231)

* allow handles to start with a number

* don't allow leading hyphen

src/lib/strings/handles.ts

@@ -3,7 +3,7 @@ export function makeValidHandle(str: string): string {
     str = str.slice(0, 20)
   }
   str = str.toLowerCase()
-  return str.replace(/^[^a-z]+/g, '').replace(/[^a-z0-9-]/g, '')
+  return str.replace(/^[^a-z0-9]+/g, '').replace(/[^a-z0-9-]/g, '')
 }
 
 export function createFullHandle(name: string, domain: string): string {