Multi-Format Encoder: compare two encodings from one input

Keep the branches as labeled independent outputs; Base64 and percent-encoding solve different transport problems and merging their text without metadata is ambiguous. Define the input character encoding and whether Base64 means the standard or URL-safe alphabet. Percent-encode a URL component, not a complete structured URL. Include original byte length and output type, enforce size limits before expansion, and round-trip each branch in tests. Encoding is reversible representation, so neither branch should be presented as secrecy or sanitization.