Add FNV-1a hash algorithm implementation with 32-bit and 64-bit variants

[dinilH]

Description

Add FNV-1a (Fowler-Noll-Vo) hash algorithm implementation to the hashes module.

Changes

• Add hashes/fnv1a.py with two functions:
  • fnv1a_32(): 32-bit FNV-1a hash
  • fnv1a_64(): 64-bit FNV-1a hash

Why this contribution?

• FNV-1a is a widely-used, fast, non-cryptographic hash function
• Missing from the current hash algorithms collection
• Educational value for understanding hash function design
• Better distribution properties than original FNV-1

Testing

• ✅ All 20 doctests pass
• ✅ Tested with various inputs (empty string, single char, long strings)
• ✅ Verified consistency (same input → same output)
• ✅ Verified differentiation (different inputs → different outputs)
• ✅ Type checking with mypy passes
• ✅ Code style checks with ruff pass

References

• Algorithm source: http://www.isthe.com/chongo/tech/comp/fnv/
• Wikipedia: https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function