feat: implement base64 algorithm based on core-js

[himself65]

No description provided.

[jazzberry-ai]

Bug Report

Name	Severity	Example test case	Description
Invalid character handling in non-strict mode	Low	import { base64 } from "./base64";\n\nit("should not throw error on invalid characters in non-strict mode", () => {\n const base64WithInvalid = "SGVsbG8s#IFdv$cmxk%IQ==";\n expect(() => base64.decode(base64WithInvalid, { strict: false })).toThrow(\n 'Invalid Base64 character: "#"',\n );\n});	The base64Decode function throws an error when encountering invalid characters even when strict is false. This is inconsistent with some Base64 implementations, where invalid characters are ignored in non-strict mode.

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