fix: validate embedding bytes length in bytes_to_embedding

[echobt]

Description

This PR addresses an issue where bytes_to_embedding would silently ignore trailing bytes that do not form a complete 4-byte chunk. This behavior could mask data corruption issues.

Changes

• Added a debug_assert! to validate that the input byte slice length is divisible by 4.
• Added unit tests to verify valid inputs and ensure invalid inputs trigger the assertion (panic in debug mode).

Verification

• Added test_bytes_to_embedding_truncation which expects a panic when input length is invalid.
• Added test_bytes_to_embedding_valid to ensure correct functionality for valid inputs.
• Ran cargo test and confirmed all tests pass.