The repository had no fuzzing setup despite several natural targets —
the CSV parser, the Binance envelope deserializer, and the stateful
indicator/aggregator update paths.
Add a fuzz/ cargo-fuzz crate (detached from the workspace via its own
[workspace] table and the parent's exclude) with four targets:
- csv_reader — CandleReader over arbitrary bytes
- binance_envelope — RawWsEnvelope deserialization from arbitrary strings
- indicator_update — RSI/EMA streaming + batch over arbitrary f64 series
- tick_aggregator — TickAggregator over arbitrary tick triples
Each target asserts the no-panic contract: malformed input must surface
as an Err. fuzz/README.md documents running them (nightly + cargo-fuzz).