add data folder README

Author: Xor-el

HashLib.Tests/Data/README.md

@@ -0,0 +1,46 @@
+# HashLib Test Data
+
+External test vectors for HashLib4Pascal unit tests.
+
+Cryptographic test corpora — especially multi-megabyte BLAKE2 known-answer JSON and
+extensible KDF CSV tables — are kept here as data files rather than embedded in Pascal
+source. Vector sets will continue to grow as more algorithms and standards land; keeping
+them outside the codebase keeps the library and test sources readable, avoids bloating
+builds with megabytes of string literals, and lets fixtures be updated or extended
+without recompiling test code.
+
+This folder holds the files the test suite loads at runtime (JSON KAT corpora, CSV test
+vectors, and related fixtures). Layout and formats are documented below.
+
+## Layout
+
+All folders and files use **PascalCase** names.
+
+```
+Data/
+└── Crypto/     Algorithm vectors (JSON, CSV)
+```
+
+### `Crypto/` subfolders
+
+| Folder | Contents |
+|--------|----------|
+| `Blake2`, `Blake3` | Hash KAT JSON vectors |
+| `Scrypt`, `Argon2`, `Pbkdf2` | Password-based KDF vectors |
+
+## Vector formats
+
+### Hash
+
+| Path | Format |
+|------|--------|
+| `Crypto/Blake2/blake2-kat.json` | BLAKE2 KAT JSON: `[{hash,in,key,out},…]` |
+| `Crypto/Blake3/test_vectors.json` | BLAKE3 test vectors: `{"cases":[{input_len,hash,keyed_hash,derive_key},…]}` |
+
+### KDF, digest, and MAC
+
+| Path | Format |
+|------|--------|
+| `Crypto/Scrypt/TestVectors.csv` | RFC 7914: `Enabled,Password,Salt,Cost,BlockSize,Parallelism,OutputLenBytes,ExpectedHex` |
+| `Crypto/Argon2/TestVectors.csv` | Argon2 test vectors |
+| `Crypto/Pbkdf2/TestVectors.csv` | RFC 6070-style: `Algorithm,PasswordHex,SaltHex,Iterations,OutputLenBytes,ExpectedHex` |