Protocol Buffer Serializer

# Protocol Buffer Serializer PRD

## Overview
Build a Protocol Buffers implementation that parses .proto schema files, serializes and deserializes messages using the protobuf binary wire format with varint encoding, and includes a schema compiler that generates TypeScript interfaces.

## Requirements
- .proto file parser supporting message, enum, oneof, nested messages, and imports
- Field types: int32, int64, uint32, float, double, bool, string, bytes, enum, and nested message
- Wire types: varint (0), 64-bit fixed (1), length-delimited (2), 32-bit fixed (5)
- Varint encoding and decoding using LEB128 format
- Zigzag encoding for signed integers (sint32, sint64)
- Field tags combining field number and wire type
- Serialization: convert a message object to its binary protobuf representation
- Deserialization: parse binary protobuf data back into a message object
- Required, optional, and repeated field handling
- Default values per field type when a field is not present in the binary data
- Packed repeated fields for numeric types (more compact encoding)
- Nested message serialization and deserialization
- Oneof fields where only one field in the group can be set at a time
- Unknown field preservation: retain unrecognized fields during deserialization
- Schema compilation: generate TypeScript interfaces from .proto definitions
- Backward compatibility: adding new fields does not break deserialization of old data
- CLI: compile proto file, encode JSON to binary, decode binary to JSON
- Handle messages up to 1MB in size

## Tech Stack
- TypeScript / Node.js
- No external protobuf libraries — raw wire format implementation required
- File system for reading .proto files and binary data

## Scoring Criteria
- **Functional (40%)**: Serialization round-trips correctly, wire format is spec-compliant, proto files parse
- **Quality (20%)**: Correct varint encoding, proper field tag handling, clean schema design
- **Fidelity (25%)**: All features including oneof, packed fields, unknown field preservation, and code generation
- **Speed (15%)**: Time bonus